Trainee Guide TR-L2-M2000
Level 2 Maintenance Training – M2000 Dispensing Systems 4-2-65 P/N 73-0018-00 (Revision B)
Information Sheet 4-15-2
PMAC Initialization (Continued)
B. PMAC Watchdog
1. The PMAC motion control board has an on-board “watchdog timer” circuit whose
job it is to detect a number of conditions that could result in a dangerous
malfunction of the equipment.
2. It provides a fail-safe shutdown to guard against:
Software or hardware malfunction.
- The timer must see a square wave input of a frequency greater than 25 Hz.
DC voltage significantly lower than 4.75 volts.
- This prevents corruption of registers due to insufficient voltage.
3. If the red LED light on the PMAC card is on, a problem is indicated.
4. If the watchdog has been tripped, power to the PMAC must be cycled off and on.
5. If the red LED stays lit on reset, you must determine whether the problem is
hardware or software related.
6. The first step is to reinitialize the PMAC.
7. If the red light remains on after you have reinitialized the PMAC, a hardware
problem is likely.
C. Reinitializing the PMAC
1. To reinitialize the PMAC, you must reset the PMAC to factory defaults.
2. Download the PMACINI.PMC file from the C:\FmNT Directory (See Exercise Sheet
4-15-1 on page 4-2-68).
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