Monday, April 25, 2011

Modicon PLC Status Display

The panel display on the front of the Micro PLCs is using LEDs to show the health and status of the unit’s CPU, communication ports, fixed I/O points, and battery.
PLC status base on the LEDs:
power ok, when internal power is OK the green LED lighted ON
ready, the amber LED lighted ON when the PLC has passed its power-up diagnostics, and remains lighted ON as long as the PLC is OK
run, the green LED lighted ON when the PLC has started to run and is solving logic when the PLC has power but do not have a valid operating mode configuration
battery low, the red LED lighted ON when the internal battery is no more power.
exp link, This LED lighted ON if it detects the problem in the optional of battery capacitor or if the capacitor is not charged fully. A green LED lighted ON steadily when occur the valid communications on the I/O expansion connecting. Same indications happen in PLCs involved in the communication.
comm 1 A green LED is flashes when communications happen on the first RS-232 port.
comm 2 A green LED is flashes when communications happen on the second RS-232 port.
The LEDs array on the left side display shows the fixed discrete I/O points status on the PLC. The physical of I/O point to a number of LED is reference in the display, referring to the diagram of wiring.

The error is detected when the run LED on the right side is flashing in conjunction with any input of LEDs. The input LED pattern flashes shows the nature of the error. The people who program the PLC can base onto the Modicon Micro Ladder Logic Manual (890 USE 146 00) for a system crash codes description.

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