Delta MMC120 - Manual (Page 67)

MMC120 Linear Motion Control Module Troubleshooting
Delta Computer Systems, Inc. 360/254-8688 67
TROUBLESHOOTING
Problems and Solutions
Ladder program cannot access parameters or operate module
1) Module not configured properly - Active LED off. Configure the module as a 4 input and 4 output
register module with binary format.
2)
Make sure the Programmable Controller is accessing the correct I/O registers.
Red LEDS 2, 3, 4, 6, 7, or 8 are on
This indicates the transducer is not responding to the module. Every millisecond the module interrogates the
transducer's position. If a return response is not seen after about two milliseconds, the internal counters
overflow, and red LED 4 or 8 will be latched. If a return response is not seen after six milliseconds, red LED
2 or 6 will be latched. If the transducer count between interrogations changes too much (indicating noise), red
LED 3 or 7 will be latched. Check the transducer power supply and check the wires to the transducer.
Red LEDS 2 and 6 are on; all other red LEDS are flashing; no green LEDS on
This indicates that the flash memory on the module has an invalid checksum. You must download a new copy
of the firmware to the module.
During a move, the Actual Position is erratic
Electrical noise or a defective transducer is usually the cause of this problem. Monitor bits 1, 2, and 3 of the
axis' STATUS word to determine if the module is detecting a transducer error. To reduce electrical noise
check the following:
1) Make sure the transducer wiring is separated from all other wiring.
2) Add a termination resistor (220 ohm for Temposonics I) as close to the transducer as possible.
3) Connect the shield at the module end, the transducer end, or both.
During a move, the drive comes to a halt for no apparent reason
When the module detects a 'transducer not responding' error it makes a Hard Stop. See 'Actual Position is
erratic' above for more information. If any of the following conditions are enabled, the axis will also halt:
Following Error
Overdrive Error
Position Overflow
Parameter Error
Stopped
Transducer counts field not indicating transducer location
See 'Axis indicator constant red' above.
Transducer counts field changes but output drive does not work
See '...drive comes to a halt for no apparent reason' above.