Delta MMC120 User Manual download pdf (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

2) Make sure the Programmable Controller is accessing the correct I/O registers.

RedLEDS2,3,4,6,7,or8areon

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.

Duringamove,theActualPositioniserratic

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.

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Delta MMC120 User Manual Page 67