Changing counter value while Hot Standby switchover



Goals and Symptoms

This resolution describes a workaround for an effect by a Hot Standby switchover with RIO and a software counter.
The RIO cable connection to the Primary CRP 931 fails.
An input from a 140 DDI 353 00 module has value "1" at the same time.
The Standby system switches to Primary (what is correct).
But the input bit gets for a short time the value "0", because the CRA is not available while switchover.

If the binary input is linked to a software counter the counter will change the value. Also affected are program parts, which use this binary input together with Edge detection.

Facts and Changes

Problem is known with the following components:
Concept 2.6 SR2
140CPU43412A, EXEC 1.25, Kernel 1.01
140CHS11000, EXEC 1.04, Kernel 1.00
140CRP93100, EXEC 1.15, Kernel 1.01
140 DDI 353 00

It should exist with all Hot Standby systems equiped with 140CRP93100, every discrete Input and a software counter or a Edge detection is linked to the Input module.

Causes and Fixes

Use the EN input of the software counter and link it to the healthy bit of the Input module. This avoids to increase the counter during RIO cable interrupt.

Legacy KB System (APS) Data: RESL167770 V1.0, Originally authored by on , Last Edited by on
Related ranges: Modicon Quantum