Discrete Inputs/Outputs Fault Diagnostics

At a Glance

The diagnostics function detects any errors that may be in progress. Three error groups can be identified:

internal errors,
external errors,
other errors.

Internal Errors

This category contains all internal module errors and all communication errors that prevent a module from operating correctly.

A communication error may be caused by a hardware error at the rack bus, or a processor or extension cable error.

External Errors

The following errors fall into this category:

terminal block error: all terminal block modules contain a device for checking the presence of a terminal block in the module. Where a terminal block is missing or badly inserted in the module, the error is detected and is alerted by the flashing of the I/O LED on the front panel of the module,
overload and short-circuit: transistor output modules contain a device for checking the load status. In the event of overload or short circuit of one or several outputs, the circuits of these will be tripped and the errors will be shown on the front panel of the module - the LEDs corresponding to the faulty outputs will flash and the red I/O LED will light up,
sensor voltage error: all input modules contain a device for checking sensor voltage for all module channels. This device checks that sensor and module power supply voltages are of a sufficiently high level to guarantee the correct operation of the module’s input channels. When sensor voltage is less than or equal to a defined threshold, the error is shown by the I/O LED lighting up on front panel of the module,
pre-actuator voltage error: all 24/48 VDC transistor output modules contain a device for checking the pre-actuator voltage of all module channels. This device checks that pre-actuator and module power supply voltages are of a sufficiently high level to guarantee the correct operation of the module’s output channels. This voltage must be greater than 18 V (24 VDC supply), 36 V (48 VDC supply) for modules with direct current transistor outputs. In the event of pre-actuator voltage being less than or equal to this threshold, outputs are set to 0 and the error is show by the I/O LED lighting up on the front panel of the module.

NOTE: The sensor/pre-actuator voltage check is unique to terminal block modules. In 32- or 34-channel connector modules, there is one checking device per connector (equivalent to one per group of 16 channels). A sensor or pre-actuator voltage error leads to all the inputs and outputs affected by the error (i.e. all channels for a terminal block module and the group(s) of 16 channels for a 32- or 64-channel connector module) to be set to faulty.

NOTE: Relay and bidirectional triode thyristor output modules do not contain pre-actuator voltage checking devices.

Other Errors

The Other errors category includes switched off modules.

Description

The following table can be used to determine the module’s status on the basis of the LEDs located on the Discrete I/O modules’ display block.

State of module		LEDs
State of module		RUN (green)	ERR (red)	I/O (red)
Normal operation
Internal errors	Module failure, no PLC communication
	Module failure, PLC communication possible
	Communication error
External errors	Terminal block error
External errors	Overload, short circuit, sensor/pre-actuator voltage error
Other errors	Module switched off

Legend:
		LED on
		LED flashing
		LED off

WARNING

CHANNEL LED INFORMATION NOT MATCHING SENSORS POSITION

After a sensor power outage:

The I/O error LED is on.
Do not take into account the input LEDs information (they show the last recorded position of the sensors, not their real positions).
Check the real positions on the sensors.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

NOTE: When the sensor detects power outage, the error LED of the following modules switchs on and the last recorded state of the sensor is displayed by the input LEDs.

The 24 VDC modules are:

TSX DEY 16D2
TSX DEY 32D2K
TSX DEY 64D2K

The 48 VDC modules are:

TSX DEY 16D3
TSX DEY 32D3K

I/O LED Behavior After Power Outage

Depending of the Supply Monitoring check box in the discrete module configuration screen, the I/O LED behavior of the module after a power outage is different.

When the Supply Monitoring check box is checked:

All inputs within a 16 channels group are forced to 0 by the CPU. As a result, the I/O default is transmitted and the I/O LED flashes.
When the Supply Monitoring check box is unchecked:

All inputs within a 16 channels group are the last state available at the power outage occurrence. As a result, the I/O default is not transmitted and the I/O LED is switched off.

In both cases, the inputs state is the last state before the sensor terminal voltage disappears.