Purpose:  Update CNC’s tool changer to function with new motion-control hardware.

Hardware:  Delta Tau manufactures a line of PMAC motion control boards.
In addition to the motion control functions, the boards also have a number of PLC emulators as a built in feature.  These PLC's may be programmed to control synchronous functions of the machine.  An important note is that the motion programs take CPU priority over PLC programs, so one should design their PLC programs accordingly
 To optically isolate the PMAC from the inputs and outputs Opto22's G4 racks and modules were used.  We used two 32 line racks, one for the inputs, and one for the outputs.
 

Action:  To retrofit the machine the existing controller was removed.  The cabinet was opened, and all control cables carefully disconnected.  At this point labeling of cables is very important, and great care should be taken to ensure labels are firmly affixed.  Due to the years of shop-floor use, the cables were grimy, and needed to be cleaned.
The cables were pulled out of the overhead conduit, and fed into the auxiliary panel that houses the Opto22 racks and PMAC controller.  Excess length of cable was cut out at this point.  The cut ends of the cables were again labeled, and the connectors were retained for their pin-out.
Using the ‘Elementary of the Control Cabinet’ print supplied by Brown and Sharpe, the cables were sorted by general function.
The function of each individual conductor was determined by examination of the supplied prints.  Each conductor was terminated in one of two Opto22 racks.  Rack A was designated the Output rack.  Rack B was designated the Input Rack.  Appendix A contains pin-outs and functions of Inputs and Outputs.

Programming:  The tool changer was run using one of the PLC emulators built into Delta Tau’s PMAC motion control board.  The program looks something like Basic, but operates more closely to ladder logic.  The program used may be viewed in
Appendix B.
 Main program - Appendix B.1                     //Sorry, not on the Web!
 Initialization program - Appendix B.2           //Sorry, not on the Web!

Testing:  All accessible inputs were actuated to ensure an input signal from the Opto22 rack.  Outputs were cycled with machine power off (control power on) to ensure their proper function.
The safety of the system was checked before putting the changer into active service.
 
 
 

Problems:  The Opto rack suggested by Delta Tau was not actually directly compatible with the PMAC board.  The pin-out of the Opto’s 50-pin connector was not the same as that of the PMAC’s.  As a remedy, an intermediate board was made to jumper the connections properly.  It is advisable and recommended to research and use a directly compatible rack in the future, and possibly exchange the current rack.  Grayhill produces a rack that uses the same G4 modules as the Opto22, and is directly compatible.
To communicate with the Opto22 racks an accessory board (Delta Tau ACC34D) was used.  The output side of the board was not functional, so another one was ordered.  This one was also shipped with a non-functional output system.  Another style of board, the Delta Tau ACC34A was used as a replacement, but it is also recommended to find a functional ACC34D in its place.