Delta Computer Systems TMC 188/40 Series Manual page 11

TMC 188/40 Motion Control Module
responsible for initializing the parameters when the TMC 188/40 is powered up. It must place the
correct values in the Special Function Interface Chip (SFIC) WY registers, write the parameter values
to V Memory, and issue a 'P' command to the MCM. The following procedure will help you determine
the optimal values for the initialization parameters.
First, disconnect the drive output from the TMC 188/40 (15 pin connector), and find a way to move
the axis by hand. Build a chart in TISOFT (or use the chart on the DCSMON disk) to monitor the
appropriate V Memory locations (see the sample V Memory map on pages 21 ans 22). Make sure
the transducers are connected and powered.
If you want to begin quickly, you can proceed to Step 6 - Moving The Axis. Continue with this section
now or return to it later to set the DIRECTION, SCALE, and OFFSET parameter values.
DIRECTION Parameter
Decide whether the ACTUAL POSITION will increase or decrease as the axis extends. (Remember -
extending is the direction that returns increasing TRANSDUCER COUNTS.) The DIRECTION
parameter should be 0 if the ACTUAL POSITION increases as the axis extends, and it must be zero
for Quadrature applications (see Appendix C). This is the default value. The DIRECTION parameter
should be set to -1 (0FFFFH) only if the ACTUAL POSITION decreases when the axis extends.
Next, have the P/C issue 'P' command (80D, 50H) in the VWRITE COMMAND field
SCALE Parameter
The SCALE parameter is used to convert the transducer or encoder counts to position units. For
magnetostrictive transducers (MDT), compute the SCALE as follows (see pages 30-31 for examples):
SCALE =
MDT Cal Number(in microseconds per inch) x 27.75MHz x Number of Recirculations
TIP: Delta's DCSMON provides an easy way to work with SCALE. Use DCSMON's commands P0 and
P1 to help calculate SCALE , OFFSET, DIRECTION, and EXTEND and RETRACT LIMITS.
For Analog and Quadrature options, see the respective appendix for SCALE information.
OFFSET Parameter
Next, the axis OFFSET must be set. The axis OFFSET is added to the position of the axis before it is
stored in the ACTUAL POSITION of V Memory. When you change the OFFSET, make sure to
change the EXTEND LIMIT and RETRACT LIMIT by the same amount. Use the following equation to
adjust the current ACTUAL POSITION:
OFFSET = Old OFFSET + Desired Position - ACTUAL POSITION
If the OFFSET is greater than 32767, subtract 65536 from the OFFSET. If the OFFSET is less than
-32768, add 65536 to the OFFSET. When the OFFSET is changed, both the EXTEND and
RETRACT limits must be adjusted accordingly. Send an Alt-P to initialize the new values. Check by
moving the axis to the extend and retract limits and make any adjustments necessary.
NOTE: 1) Do not use the OFFSET parameter to compensate for severe mechanical misalignment. The
physical system must be aligned before the OFFSET parameter is adjusted.
2) After adjusting the DIRECTION, SCALE and OFFSET, be sure to adjust the EXTEND and
RETRACT LIMITS as described below. See Appendix D for more information.
Delta Computer Systems, Inc. 360/254-8688
32768 x Position Units per inch
Getting Started
11