Delta MMC120 - Manual (Page 22)

Startup MMC120 Linear Motion Control Module
22 Delta Computer Systems, Inc. 360/254-8688
STARTUP
CAUTION: Do not connect the drive outputs to the drives until the EXTEND and RETRACT limits have been
determined and the MMC120 has been properly initialized with these limits by the Quantum
Programmable Controller.
Great care must be taken to avoid accidents when starting the Motion Control Module for the first time.
The most common accident is a runaway, where the motion controller tries to go to a position beyond the
physical limits of an axis.
When the MMC120 Motion Control Module is first turned on the parameters are set to default values. These
values allow the module to maintain the present positions of the axes it controls; the parameters must be
changed for the module to work in your system. The Quantum Programmable Controller program is
responsible for initializing the parameters when the MMC120 is powered up by sending the correct
initialization parameters to the module, then issuing a 'P' command. The following procedure will help find
the optimum values for the initialization parameters.
TIP: Use Delta's DCS120 setup program to help determine initial parameters and operation. Also, Delta's SSS/10
Servo System Simulator and PPS/14 Position/Pressure Simulator provide a simple way to test your program
before connecting the module to a real system. See APPENDIX A: DCS120 DIAGNOSTIC AND SETUP
PROGRAM.
Configure DCS120 to communicate with the module. Make sure the transducers are connected and powered
up. Disconnect the drive output from the MMC120 (3 pin connector), and arrange a way to manually move
the axis, either physically or with a control box that can electrically drive the valve (a 'diddle box'). If neither
of these options are usable to you, the procedure shown in 'Moving the Axis' (pages 21 and 22) uses DCS120
and the Open Loop mode to slowly move the axis.
Initialization Parameters
If you want to get started quickly, go to the next section - Moving The Axis. Continue with this section now
or return to it later to set the SCALE and OFFSET parameters.
The easiest way to set the SCALE and OFFSET is to use the P0 and P1 commands in DCS120. To use these
commands, you need to know the physical position and the corresponding transducer counts at two points
(usually the extend and retract limits). For example, if the first position is 0.000 inches and the counts are
2163, and the second position is 27.500 inches and the counts are 31626, then enter:
P0 0 2163
P1 27500 31626
After you enter values for both P0 and P1, the SCALE and OFFSET fields will be updated on the screen
(notice the parameters turn gray). Use the alt-P command to activate the new values. See Appendix A for
more information about the P0 and P1 commands.