How to Modify the Fallback Mode Parameter for a Discrete Output TBX Module

At a Glance

This parameter defines the fallback mode adopted by outputs when the PLC changes to Stop, in the event of a processor, rack or inter-rack cable fault.

The possible modes are as follows:

Mode	Meaning
Fallback	The channels are set to 0 or 1 depending on the fallback value set for the group of 8 corresponding channels.
Maintain	The outputs remain in the status they were in before switching to Stop.

WARNING

UNEXPECTED APPLICATION BEHAVIOR

Ensure that the extension module is connected to the base module via the connection cable, else the extension module outputs would not switch to fallback mode.

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

Procedure

The table below shows the procedure for defining the Fallback mode assigned to a group of channels.

Step	Action
1	Access the hardware configuration screen of the required module.
2	In the channel area, select the required channel group.
3	In the General parameters area, click on the drop-down menu button in the Fallback mode field. Result: a drop-down list appears.
4	Select the required fallback mode.
5	For the Fallback mode, configure each channel of the selected group. To do this, click on the drop-down menu button in the Fallback value column of the configuration area.
6	Click on the required value (0 or 1).