Inter-Modular Bus Timeout

The Inter-Modular Bus Timeout (IMBTO) is a timer run internally within each I/O module from start‑up. The following syntax is used for the Inter-Modular Bus Timeout:

If the TMR Processor does not scan the module within the programmed time, the module adopts the shutdown mode. In the majority of

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Systems, omit using this timeout and instead use the default value. In systems that are very large, or for test purposes, for example to pause application program, adjust the timeout period. The timeout period is defined in milliseconds; a value of zero disables the timeout.

For the IMB timeout, it is recommended to poll the module at least four times at the normal scan time within the timeout, taking scheduled polling into account. Example: if the current scan time is 200 milliseconds and the module is set for scheduled polling at every 5th scan, set the timeout to 200 x 5 x 4 = 4000ms minimum. Ensure that the timeout is still safe by setting the timeout to less than half the process safety time.