Checking the Discrete Input / Output connection

At a Glance

In order to check the I/O connection, ensure that:

sensor data is registered by the corresponding inputs and the processor,
control orders from the processor are registered by the outputs and transmitted to the corresponding pre-actuators.

WARNING

UNEXPECTED SYSTEM BEHAVIOR

Active outputs can activate machine movements.

Turn all power off before checking the Discrete I/O connection:

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

Description

It is possible to check the connection of the Discrete I/O modules:

without a terminal:
- by activating each sensor and checking whether the corresponding input LED changes status. If it remains unchanged, check the wiring and correct operation of the sensor.
using the terminal:
- using a terminal, it is possible to perform a more comprehensive I/O check. To do this, an application with configured I/Os at minimum (an empty application is sufficient but if the application is empty no module should be declared in the ’FAST task’) should be previously loaded onto the PLC from a programming terminal,
- this check can be carried out, with the PLC in RUN mode, from a PC equipped with Control Expert software giving access to debug functions,
- this check can also be carried out with the entire application loaded in the memory. In this case, stop the processing of the program by de-activating the MAST, FAST and event tasks by setting system bits %S30, %S31, %S38 to 0.

Input check

The following table shows the procedure for checking input connections.

Step	Action
1	Activate each sensor and check that the corresponding input LED changes status.
2	Check on the terminal screen that the corresponding input bit (%I•) also changes status.

Output check

The following table shows the procedure for checking output connections.

Step	Action
1	From the terminal, set each bit (%Q•) that corresponds to an output to 1 then 0.
2	Check that the corresponding output LED turns on then off and that the corresponding pre-actuator activates then de-activates.