Soft-Wired Machine Tool Control

1. Field of the Invention

This invention relates generally to machine tools and more particularly to controls for positioning a workpiece or working component of the machine tool.

2. Description of the Prior Art

Much has been done in the field of numerical control of machine tools. Some U.S. Pat. Nos. which have issued on this subject in the United States are as follows:

3,555,516 - Proctor

3,573,737 - Rosenberg

3,576,540 - Fair et al

3,576,979 - McCall et al

3,626,385 - Bouman

3,634,661 - Fitzner

3,634,662 - Slawson

3,653,072 - Ballas et al

3,668,653 - Fair et al

3,720,814 - Klein

3,720,817 - Dinwiddie

3,725,651 - Cutler

3,725,652 - Knovalina

3,727,191 - McGee

3,739,158 - Woodward

3,746,845 - Henegar et al

3,763,360 - Nishimura et al

3,770,947 - Deily

3,784,798 - Beadle et al

3,812,474 - Linn et al

3,827,030 - Seipp

3,843,875 - Goodstal et al

3,849,712 - Lankford et al

3,670,153 - Rempert et al

In addition, there is now offered a hardwired solid-state controller for new milling machines by Cincinnati Milacron Company of Cincinnati, Ohio, where the control panel is pendant-mounted, as is a Cybelec (Swiss) back gauge control panel.

While several of the above patents and machines on the market employ controls with programs on cards or magnetic or paper tapes, the equipment required is often large and too expensive for economical adoption by the prospective customer. Furthermore, much of it, while available on new machine tools, is not adaptable to existing machine tools. Yet there are many machine tools throughout the world which could be greatly improved in utility if provided with economical numercial controls.

Several steps in this direction have been taken already and are represented by the U.S. Pat. of Gerald V. Roch, No. 3,618,349 for GAUGING SYSTEM FOR PRESSES issued Nov. 9, 1971. That patent describes manually pre-programmable front and rear gauging for press brakes and which could be readily retrofitted to existing press brakes. A more recent advancement is diclosed in the U.S. Pat. of Gerald V. Roch and Edward H. Sonn, No. 3,874,205 entitled DIGITALLY CONTROLLED MULTIPLE DEPTH STOP AND RETURN STROKE LIMIT CONTROL FOR PRESS BRAKES and issued Apr. 1, 1975. This can be retrofitted also to press brakes for pre-selecting various ram stroke depth and return stroke travel dimensions. There has remained a need for more options in such equipment at lower cost, and a more compact control panel readily movable in accordance with the wishes of the operator. The present invention is intended to answer at least some of these additional needs.

Described briefly in the illustrated embodiment of the invention, a pendant control box and panel conveniently mounted to the machine tool has arrays of buttons thereon for entry of data and instructions for control of such functions as front and rear gauge positions and ram limits for a press brake, for example. The control box has a controller therein, including at least one programmed memory chip, a random excess memory chip to store data manually entered, according to the instructions, also manually entered. A microprocessor executes according to a program stored in the programmed memory, and according to instructions and, operating through various peripheral interface adapters, provides the displays of information and the control signals to motor drives for positioning front and rear gauges, ram or other machine tool components, according to the particular application.

FIG. 1 is a general perspective view of a press brake incorporating a typical embodiment of the present invention thereon.

FIG. 2 is a major component block diagram.

FIG. 3 is an enlarged view of the control panel.

FIG. 4 is a block diagram of the control cabinet contents.

FIG. 5 is a flow chart.

FIG. 6 is a functional block diagram of the microprocessor and peripherals.

FIG. 7A is a logic diagram identifying the connections of the microprocessor unit (MPU) with the random access memory (RAM) and read only memory (ROM).

FIG. 7B is a schematic-logic diagram of coupling of PIA #1 with drivers for part of the incandescent display, with terminals for the LED display, and identifying the connections of PIA 1 to the MPU.

FIG. 7C is a logic diagram of the LED display and driver.

FIGS. 7D and 7E are two portions of a logic diagram of the switch scanning multiplexers, identifying the connections of PIA #2 to the MPU.

FIG. 7F is a logic diagram of the rear-gauge position and direction sensing and motor control, identifying the connections of PIA #3 to the MPU.

FIG. 7G is a logic diagram of the depth stop limit switch selection relay and indicator lamp drive, identifying the connections of PIA #5 to the MPU .

Appendix A is a brief narration of a program useful with the controller in a typical embodiment of the invention having the multiple depth stop type of ram control.

Appendix B is the program itself using the Motorola M6800 microprocessor instruction code.

Referring to FIG. 1 which shows a preferred embodiment of the present invention as applied to a press brake, the press brake 11 has a bed 12, ram 13, and side frames 14. The ram can be hydraulically or mechanically driven. There is a back gauge 16 mounted to the bed behind the lower die 17, and a front gauge 18 mounted to the bed in front of the lower die 17. Both gauges can be driven by linear lead screws driven by electrical motors as at 19 driving screw 19S which motors are servocontrolled and have shaft angle encoders as at 20 to count the turns of the shaft as driven by the lead screw. The ram 13 may be driven by a pair of hydraulic cylinders 21.

A pendant control cabinet 22 is swivel mounted to an arm 23 at 24 which swivels at 24A to arm 23A swivel mounted to the fixed upper cross member 26 or side frame of the press brake. A power supply and amplifier box or cabinet 27 may be provided at any suitable location. A series of depth stop limit switches can be provided as at 28 similar, for example, to the arrangement shown in U.S. Pat. No. 3,824,822.

Referring to FIG. 2, where power and signal transmission couplings are represented by lines between blocks, 115 volt AC electrical energy is supplied to the apparatus through the power supply and amplifier box 27 at 31, and 24 volt DC is supplied from there to the pendant control 22 through cable 32. Cable 32 may extend through the interior of the arm 23 along with conductors for ram digital control, ram depth stop control, and front and rear gauge control. Cables 33 and 34 between the power supply box and the front and rear gauges respectively, carry conductors for gauge motor drive, encoders, tachometers, and limit switches. Cables 35, 36 and 37 from the ram depth stop switches 28, digital encoder 51, and ram limit switch 31 are conveniently handled through the power supply box for coupling to the control cabinet 22.

Referring now to FIG. 3, there is shown the front panel 22F of the control cabinet or pendant 22. A switch 38 is provided to connect and disconnect electrical power from the entire apparatus. A keylock switch 39 is provided to enable the choice between English or metric dimensions for entry of data in either inches or millimeters. It also provides for display of the entered data in the dimension data window 41 in either inches or millimeters. A set of light-emitting diodes (LEDs) is provided behind this window as is true also of the station indicating window 42 and the cycle indicating window 43. These three windows provide the LED displays.

Another type of display is provided on the backlighted display panel 44 in which there are legends as shown in FIG. 3, with each of the legends having an independently illuminated incandescent bulb in one "cell" of an egg-crate shield assembly, behind the panel to illuminate one or more of the legends depending on which lamps are lighted in accordance with the state of operation of the control.

A four position rotatable mode switch 46 is provided, the four positions of which enable selection of one of four modes, two of them being in the "DATA" category for the data entry mode ("ENTER") and for the data check mode ("CHECK") and two of them in the "PROGRAM" condition category, one of which is "IDLE" and the other of which is "OPERATE."

Immediately to the right of the mode switch 46 there is a ram function column of switches 47 having four switch-operating keys or buttons therein with labels thereon as shown. Immediately to the right of that is a bank 48 of data entry switch buttons, ten of which have numerals therein for entry of numbers, and four of which have letter legends thereon to designate a category of data for the numbers to be entered by the button-operated switches in the keyboard switch bank 48. Immediately to the right of this bank of 16 buttons there is a miscellaneous function bank 49 of push button operated switches, the four buttons of which have legends on the faces thereof.

Across the bottom of the panel there are four buttons identified "MASTER CLEAR," "START," "STOP," and "EMERGENCY STOP." The "MASTER CLEAR" button being guarded, is not susceptible to being pushed by brushing against it or otherwise than by a deliberate manual act, and thus not accidentally.

In contrast with the apparatus described in the abovementioned Roch patent, where digital thumbwheel switches were set for each digit of a dimension to be used, and for each different position at which a gauge or movable workpiece stop is to be located during the making of a bend in the workpiece, the present invention provides the keyboard 48 by which the dimensions can be entered into a memory and the number of the station at which each of the dimensions is entered can be entered along with the dimension. The illustrated keyboard includes momentary-contact proximity switch operating push buttons with nine positive integers and zero thereon as shown in FIG. 3. Some users may prefer that discernible button movement be provided for switching during pushing. Others may prefer that a push as light as the mere touch of the button, with no discernible movement thereof, accomplish the switching. So it is that various types of momentary contact type switching can be employed to enter data in the memory. Therefore, the number of digits in a dimension is not limited by the number of buttons, or by the number of digital thumbwheel switches as was true in the above-mentioned Roch U.S. Pat. No. 3,618,349, nor is the number of stations limited by the number of sets of digital thumbwheel switches, which was six sets in that patent. Therefore, the present invention can be employed to enter dimenions for any number of stations, depending upon the capacity of the memory components selected, and sixteen stations would be one example of a suitable number. This would make possible selection of sixteen different points at which a gauge could be located to serve for making a particular bend in a workpiece in a press brake. Also, the number of stations can be distributed as desired between front and back gauges, where the unit is equipped with both front and back gauges. For example, ten bends could be made with ten different back gauge positions, and six bends employing the front gauge or gauges at six different positions.

To better appreciate the purpose of the various switches, buttons, and legends, the various functions thereof will now be described with reference to the application of the illustrated embodiment to front and back gauge assemblies as applied to a press brake such as, for example, in the aforementioned U.S. Pat. No. 3,618,349 and as applied to depth stop and return stroke limit control as described in the above-mentioned U.S. Pat. No. 3,874,205, and in a leaflet entitled "First Two-Axis NC for Hydraulic Press Brakes" distributed by Hurco Manufacturing Company, Inc., in October of 1973.

The apparatus is energized by pushing the master power switch 38 to the "ON" position. Switch 39 is placed in the appropriate position, depending upon whether data is to be entered in inches or millimeters. The mode switch is placed in the "ENTER" position, and the station select button "S" in group 48 is pushed. Then the number "1" is entered by pushing the "1" button in group 48 to designate that the data to be entered is for station 1 in the control sequence. At that point the station window has the number "1" displayed therein, and the "STA" window in the function display panel 44 is illuminated.

Then the cycles button "C" in group 48 is pushed, and one of the numbered buttons in that group is then pushed depending upon the number of times in the press brake sequence the same gauge dimension is to be used. In other words, the number of times that the ram is to descend to make a bend in the workpiece, without changing the gauge position, is entered in the data entry keyboard 48 after the cycle switch button "C" is pushed for station 1. That number is then displayed in the cycle window 43, and the cycle window in the function display 44 is illuminated, the station legend being still illuminated in the function display 44 and the station number appearing in station display window 42. The number of cycles which can be employed will depend upon the capacity of the memory and other hardware.

Next, the "G" button on the data keyboard 44 is pushed, whereupon the "GAGE-DIM" legend in the function display panel 44 is illuminated, and then five keys in the data entry keyboard 48 are pushed to enter the five digits representing the gauge location, such as 13.755 for example. These digits are then displayed in the dimension display window 41.

If a bend allowance is to be applied to the gauge dimension, the "BA" button is pushed, lighting the "BEND ALLOW" legend in the panel 44 and extinguishing the "GAGE-DIM" legend. Then the keys in the data board 48 are pushed to enter the bend allowance number, and that number is displayed in the dimension window 41. The bend allowance programmed for any station will be automatically subtracted from each gauge dimension programmed.

If a mistake has been made in the entry of data, the particular function in which the mistake has been made is selected by pushing the function button such as "G" in group 48 for gauge data entry, or "C" for cycle data entry, or "BA" for bend allowance data entry, and then pushing the "CL" button in the miscellaneous function column 49. Then, for the particular data to be corrected, the appropriate button such as "G", "C", or "BA" is pushed again, and the numbered buttons appropriate to the correct data are again pushed for entry of the correct data. If it happens that the operator wishes to clear all data which has been entered from the beginning of entry of data, the program clear button, identified "MASTER CLEAR" in the lower group, is pushed, and it clears all information from the random access memory.

After all of the data appropriate to station 1 has been entered, then the station button "S" is again pushed, and the number 2 button in group 48 is pushed, and the same sequence of entering data, cycles, gauge, and bend allowance, if any, is entered as discussed above with respect to station 1. The same procedure is performed for all of the stations to be programmed in the controller.

If it happens that the controller is equipped with the ram control option, some additional entries are made for each station. This will now be described.

As mentioned briefly above, the control of the present invention is applicable to control of the ram of a press brake, regardless of whether the control be accomplished by the use of a rotary encoder for sensing the up and down travel of the ram, or the use of a number of different depth stops and limit switches associated therewith and various enabling and disabling circuits for sequentially enabling and disabling the limit switches according to the particular depth stop to be employed for control of the ram at any given stroke.

Considering first the application of the control to the press brake where equipped with a rotary encoder on the upper cross member 26 and an encoder drive rod 52 secured to the ram, following the selection of the station, the number of cycles for that station, and entry of the gauge dimension and any bend allowance for that station, some further entries are made. These are made in association with the use of buttons in the ram function control button column 47. In this column there is a "U" button for use in entry of the dimension for the upstroke of the ram, a "D" button for entry of the dimension of the downstroke of the ram, an "Off" button for entry of an offset dimension, and a "Cal" button for establishing a dimensional reference point for the ram in accordance with the tooling employed in the press brake. Therefore, in the same manner as dimensional data was entered on the keyboard 48, subsequent to pushing the "G" button, the upstroke dimensional data for the ram can be entered for a given station following the pushing of the button "U". The downstroke dimensional data can be entered on panel 48 after pushing the "D" button. The offset dimension can be entered on keyboard 48 following the pushing of the "OFF" button. The offset dimension is one which is determined by experience with the particular press brake involved on the various kinds and thicknesses of workpiece materials used, in order to provide an electrical signal to the press brake control circuitry soon enough to compensate for coasting effects of the ram, and stop the ram at the right location, thereby providing the proper closure for the ram at all stations regardless of whether programmed for full depth bending operations, or for "air bending" operations where the dies are not closed completely to make a band of less than the included angle in the "V" die.

If the press brake is equipped with a depth stop type of ram control such as in a Pacific brand hydraulic press brake with automatic multiple depth stop, Model 135-N, Ser. No. 3617, for example, or as in the above-mentioned U.S. Pat. No. 3,824,822, the buttons in group 47 are not used, but instead the "DS" button in the miscellaneous function group 49 is employed. Then, depending upon the particular depth stop which is to be used for the station involved, one of the buttons on keyboard 48 is depressed to select that particular depth stop. The depth stop lamp and the numeral corresponding to the button depressed, will be illuminated in the display panel 44. In this way, the control is set up to select a particular relay for that station, the relay being activated in response to operation of one of the limit switches 28 by a manually pre-adjusted micrometer 28A, for example, to stop descent of the ram at the correct location.

Two additional buttons in group 49 are the "R" button and the "F" button. The "R" button is a button used during the programming so that if, for the bend to be made at one station, the bend made for the preceding station was such as to require removal of the part for some other handling that necessitates full retraction of the gauge involved for the new dimension to be used, by pushing the "R" button, the gauge will retract fully before advancing to the dimension being put in the station at which the "R" button is pushed. In the display panel 44, the "RET" window is illuminated while the gauge retract function is taking place.

The "F" button in group 49 designates that the data being entered for a station is for the front gauge and this button may be pushed instead of the "G" button. Otherwise, all data are assumed to be entered for control of a rear gauge. There is a "FRONT GAGE" window in panel 44 which is lighted when the machine is in the operating mode to indicate that for that particular station the front gauge is the one to be used.

If the mode switch 46 is placed in the "CHECK" position, one can review all of the data entered. By selecting the station, which involves pushing the "S" button and one of the numbered buttons in the data keyboard 48, the control will display the station number in window 42, the number of cycles in window 43, the gauge dimension data in window 41, and the "FRONT GAGE" window in the panel 44 will be illuminated if it is a front gauge which was selected for that station. If a depth stop arrangement is employed, the number of the depth stop selected will appear in window 44 according to which depth stop is involved for that particular station.

The display will be maintained until the station button is pressed again. Then, to go to the next sequential station, the "S" button is again pressed, whereupon the display for that station begins and for each function the appropriate data is presented and appropriate windows are illuminated.

When the mode switch is in the "IDLE" position, the controller maintains servo drive and memory to the last position made during the "OPERATE" mode. Data cannot be entered, nor can any operations be performed. Although the power is on and the memories retain all information therein, nothing can happen. Thus the operator can leave the controller for a break or a change of shifts without worrying about someone approaching the controller, pushing buttons, and destroying data or causing the machine to function.

When the mode switch 46 is in the "OPERATE" position, data which has been entered is now capable of being executed or performed. This is accomplished by pushing the station button "S" and then the station number button in the data board. That station number is then displayed in window 42; the program therefor is displayed in window 41; the number of cycles at which that dimension is to be used in displayed in window 43; and if the operator is satisfied that everything is correct, he depresses the "START" button in the bottom row of buttons. As soon as he does that, the "AUTO" window in panel 44 is illuminated, and the designated gauge moves to the programmed dimension. As soon as it reaches the programmed dimension, within a predetermined tolerance band, the "GAGE SET" window in panel 44 is illuminated. Then, by operating the foot pedal or other means for causing the ram to descend, the operator can make the first bend. If the ram control option is used with an hydraulic press brake, the ram will descend to the dimension selected therefor and return when the operator lifts his foot from the control pedal, or automatically if the press brake is set up for automatic return. When the ram descends to the selected dimension, within a predetermined tolerance band, the "RAM SET" window in panel 44 will be illuminated. When the ram rises, it will rise to the "UP" dimension previously entered for that station. Then the controller will advance. It will advance to the second cycle for the first station if more than one operation is to be performed with the gauge dimension selected for the first station. On the other hand, if only the one cycle was selected for the first station, the control will then advance to the next station and move the gauge designated for that station to the appropriate position for that station according to the pre-programmed data in the memory. If the gauge used during the preceding station is not to be used in the subsequent station, that gauge will retract fully and automatically. On the other hand, if the gauge will be the same gauge, but full retract is nevertheless necessary, the prior instruction by having pushed the retract button "R" during the entry of data for the second station, will cause the gauge to retract fully. It will stay fully retracted for a predetermined delay of ten seconds, for example, and then again position to the next programmed dimension.

The operations will continue until all of the stations which have been programmed, and all of the cycles for the last station in the program, have been completed, with an operation of the ram between each cycle and the next cycle. The ram operation is always manually initiated, in order to be certain that the operator has had time to place the workpiece correctly against the gauge involved and get his hands clear of the dies. Thus there is no sacrifice in safety. The "Stop" button in the lower row of four is a program stop button and, when pushed, stops execution of the program after completion of the execution of the data for the particular station and cycle being executed at the time of pressing the program stop button. To start up again, the operator must select the station involved and then push the "Start" button in the lower row of buttons. If the operator was going from station 2 to station 3 and failed to get the part out when the gauge was retracted, and the gauge is moving into the position for station 3, he pushes the program stop button and the gauge will stop when the positioning for station 3 is finished. Then, if he wants to go back to station 2, he pushes the station button "S" and then the number "2" button in the keyboard 28, and then the "Start" button. To select station 3, he pushes the "S" button and the "3" button, and then the "Start" button.

For the inch-metric mode selection, and considering the capability of entering dimensions in five digits, a decimal point will be displayed in window 41 at the correct location, depending upon whether the inch or metric mode is selected, the decimal point display being hard-wired to the switch so it is located where it should be. The operator can enter data in either dimension, and subsequently display it in the other dimension. For example, if he has a drawing which is dimensioned in millimeters and he wants to enter the program in millimeters, but wants to inspect it in inches because the inspection tool is in the English units, the inch dimension can be displayed in window 41 by switching the switch 39 to the inch position.

The controller hardware is implemented with the M-6800 "family" of micro-computer components marketed by Motorola, Inc. and described in the Micro-Computer System Reference Handbook published in 1974 by Motorola, Inc. Peripheral interface adapters (PIAs) are used. PIA 2 (FIG. 6) is used for the keyboard switches. PIA 1 is for the incandescent and LED lamps in the displays. One of the LEDs is used for the cycle indication, five for the dimension indication, and two for the station indication. PIA 3 is used for the rear gauge control, PIA 4 for the front gauge control, and PIA 5 for the ram option or for the depth stop option. Normally one would not use both options in a given application of the controller to a machine tool.

Where the gauges are driven by screws, shaft angle encoders can be used to provide input representative of amount and direction of gauge motion. For the ram, the encoder 51, driven by the drive rod 52 mentioned above, can be employed.

Two additional buttons on the control panel which have not yet been discussed in any detail are the "MASTER CLEAR" button which, when pushed, will clear all of the data from the random access memories of the control. The "EMERGENCY STOP" button will stop all operations of gauges immediately upon pushing the button.

The asterisk button in keyboard 48 could be used as a delimiter. At the end of a program sequence for a particular station during the "ENTRY" mode, the delimiter button can be pressed, allowing the operator to use in the "OPERATE" mode a series of stations successively and repetitively as a group, without disturbing other workpiece gauging programs stored in the memory and involving other stations.

From the foregoing description, it should be recognized that the present invention provides an optimum in versatility of equipment, with a minimum of size, by incorporation of the entire control in the pendant control unit 22 of compact size and convenient location, employing the attributes of the Motorola M-6800 "family" of components. The pendant control unit itself is very small, being preferably 161/2 inches wide, 9 inches high, and 71/2 inches from front to rear.

Referring now to FIGS. 7A through 7F, in FIG. 7A the MPU, RAM and ROM are shown, with the leads from the pins of the RAM and ROM labeled to show the pins of the MPU to which they are attached. The power on switch 38 (FIG. 3) is connected to the RES input of the MPU. The VMA .phi.2 output from the AND gate shown below the MPU is the memory timing signal and is coupled to the PIA's and inverted to the RAM. In the interest of speed, it is reproduced in the AND gate shown below the ROM and applied to enable input of the ROM. The inputs to the gate are from the MPU as indicated by the legend "MPU" and associated arrow. This legend is used above or below the columns of indicia at the leads outside the ROM and RAM, designating the terminals of the MPU to which the leads are attached. An input from an appropriate power failure detection circuit can be applied to the input E of the RAM to shut off the RAM and thereby protect against loss of stored data in the event of imminent power failure.

FIG. 7B shows the PIA #1 and its connection to the MPU (labels on leads to left of the PIA), its couplings to certain bulbs of the incandescent display (each bulb except BL and F having abbreviated indicia corresponding to the legends in the backlighted display panel 44 of FIG. 3), and its couplings to jacks for the LED display of FIG. 7C. The input through jack J2-15 to the driver IC1 is for the depth stop bulb DS and is obtained from the "Depth Stop" line in FIG. 7G. Bulb BL for a battery low indication, and F for front gauge selection and operation would replace two of the bulbs in the Depth Stop or ram up or down groups, depending on whether or not the press brake was equipped with the depth stops. The low battery indication is useful where batteries are to be used to preserve data in the RAM in the event of power failure. A low battery detection circuit can be used to provide the signal through jack J1-13 to the driver IC1 for bulb BL when the battery voltage is below an acceptable level. The signal for the F bulb through jack J1-14 would be provided from PIA #4 (FIG. 6) but which is not shown in detail here as it would be essentially the same as FIG. 7F.

The timer in FIG. 7B is used to provide signals for various timed events, including the retract time delay signals to PIA #2 and MUX 4 for providing the delay referred to above during which a gauge is fully retracted following a stroke of the ram, prior to moving to the next programmed dimension for the gauge. The blanking output is for blanking the LED display when it is not being scanned, and is applied through the "Timer Input" line to the decoder driver IC1 of FIG. 7C.

In FIG. 7C, one LED (S1) and the connections to it, are shown in detail. The other seven LED's are shown in dotted lines in a box. It should be understood that the MC 14511 Decode/Driver is connected to all eight LED's in the same way. This decode driver determines which segments of each LED are lighted. The octal/decimal decoder determines which LED's are lighted. The two LED's S1 and S.sub.o are for station number designation. C1 is for cycle number designation. The rest are for dimension designations. The inverter IC4 is used to respond to the inch/mm switch 39 of FIG. 3 to shift the decimal point between LED's D3 and D2. The LED's are scanned for energization one at a time.

In FIGS. 7D and 7E, some connections of wires from the multiplexers to the PIA are omitted, to avoid undue crowding. Instead, numerical reference is made. For example, at pin 6 of PIA #2, reference is made to "4-Z" meaning MUX 4, terminal Z. Similarly, at terminal Z of MUX 4, reference is made to "PIA2-6" referring to PIA #2, pin 6.

The lines to the right of the multiplexers are labelled with their function. Most go to switches. Typically, closing the switch zero grounds the line. As an example of the labelling, the "9" line from MUX 1 terminal 1 goes to push button switch "9" in array 48 of FIG. 3. The "DS" line goes to the depth stop "DS" push button in array 49 of FIG. 3. The "Check" line goes to the "CHECK" switch portion of the mode switch 46 of FIG. 3.

The label B.G.L.S.E. "2" stands for back gauge lead screw error of 0.002 inches in eight inches of length. Thus, if the gauge drive screw 19S (FIG. 1) for the back gauge which a particular control is to be used with has a nominal length of 24 inches, but is 0.006 inches longer, then a strap is tied between this line and ground. If it is 0.006 inches shorter than 24 inches, then a strap is tied between the B.G.L.S. ERROR "SIGN" line from terminal 4 of MUX 4 to ground. Provisions are made for different errors, such as "1" (MUX .phi.), "4" (MUX 2), "8" (MUX 3). Like provisions are made to compensate for lead screw errors for front gauges.

Strapping provisions are also made to tailor the control to the particular lead screw length for the back gauge and for the front gauge. For example, where the back gauge has a drive screw length of 12 inches, the "Back Gauge Length `1`" line is strapped. For a screw length of 24 inches, the "Back Gauge Length `2`" line from pin 7 of MUX 1 is strapped. Like provisions are made for front gauge length. As is true for the PIA, some lines for the MUX's are not used, but are available for other functions which could be programmed into the controller. The "ram type" lines from MUX 5 and 6 may be strapped or not, depending on whether the ram is controlled by depth stops or the digital ram control option is used.

In FIG. 7F, PIA #3 is coupled through the digital to analog converter DAC02 to the rear gauge drive motor controller of conventional manufacture. The voltage level is determined by the computer for speed control. The rotary encoder 20 provides outputs to the shift register MC14035 which is coupled to the 1 of 8 decoder to determine direction of gauge movement, the amount of which is stored in the U/D counter which serves as a buffer to keep track of gauge position while the MPU is processing other data. Four inputs to the PIA #3 provide gauge limit and reference position information. These include inputs from the plus and minus overtravel limit switches +OT and -OT at opposite extremes of gauge travel, and the center switch CS at the center of gauge travel. Coincidence of a center switch input and a shaft angle marker pulse through jack J15-5 is used to establish a precise point from which all moves are referenced. A similar arrangement can be used for a front gauge or gauges.

In FIG. 7G, like on previous figures, the labels on the lines to the left of PIA #5 identify the terminals of the MPU to which they are attached. The outputs to one of the two decoder drivers select which one of the depth stop switches 28 will control any given ram downstroke. The outputs to the other of the decoder drivers illuminate one of the six indicator lamps in the function display 44, depending on which of the depths stops is limiting the ram downstroke.

The program of Appendix B is related to the narration in Appendix A, by line numbers. Such programs can be used with a General Electric time sharing terminal and a Motorola M6800 cross assembler to produce the machine code. Procedures for use of this in simulation and verification and editing and programming the ROM are well known, and some are described in the aforementioned Motorola Micro Computer System Reference Handbook. ##SPC1## ##SPC2##