At a Glance

The diagnostics function detects any conditions that may affect module operation. Three diagnostic groups can be identified:

• internal events

• external events

• other events

Internal Events

Internal events concern all internal module conditions and all communication loss occurrences that prevent a discrete input/output module from operating correctly.

A communication loss can be caused by:

• a hardware detected fault at rack bus level

• a processor malfunction or power cable circuit open or short

• a power cable circuit open or short

External Events

External events include:

• Overload and Short-Circuit: Static output modules contain a device for checking the load status. In the event of an overload or short-circuit of one or more outputs, they are tripped to open circuit. The status will be shown on the front panel of the module - the LEDs corresponding to the tripped 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 for correct operation of the module’s input channels. When sensor voltage is less than or equal to the defined threshold, the status is shown by the I/O LED lighting up on front panel of the module.

• Pre-actuator Voltage Error: All 24 VDC and 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 for correct operation of the module’s output channels. This voltage must be greater than 18 V (24 VDC supply) or 36 V (48 VDC supply) for modules with direct current static outputs. In the event of pre-actuator voltage being less than or equal to this threshold, the error is shown by the I/O LED lighting up on the front panel of the module.

• Open wire Error: Some modules (for example BMXDAI1614/DAI1615) can detect the open wire error by checking the leakage current in the loop. In order to get the appropriate leakage current, an external resistor might be required. See details in the characteristic page of the specific module.

After a power sensor outage, if the Supply monitoring check box is not selected in the module configuration screen then the digital input can stay active.

To access the Supply monitoring check box, refer to chapter How to Modify the External Power Supply Error Monitoring Parameter.

Other Events

The other errors category includes loss of power to the modules.

Description

The following table can be used to determine the module’s status on the basis of the LEDs located on the discrete input/output modules’ display panel.