Cimplicity controlling redundancy between 90-30 PLC's

[Valter F. J. Carvalho 0]

Hello, I have the following problem: My costumer have a system configured as follows: - Two set`s of 90-30 controller + IO's. - Engineering and backup station running Cimplicity version 6.0 The set's of PLC's work in a cold-stanby redundancy, and follows these rules: Each set has it's own I/O. Each controller has access to it's own I/O only. The process of switching is controlled by Cimplicity. And we have the following problem: The redundancy control in the Cimplicity software uses a preferred PLC (primary PLC), which has the control unless it goes down. That means, if PLC A is the primary and PLC B the secondary, when we get PLC A down, the control is set (by Cimplicity) to the PLC B. But when we fix PLC A problem and put it on line again, the Cimplicity automatically set it to the controlling position. This way, since the stand by is in cold mode (that means, each time it changes, we have many data to be restored from Cimplicity and from a Oracle database, prior to the start of control), when we have a shutdown in PLC A, we have to loose time while switching to PLC B, and loose time again, when PLC A is set back. So, I got these questions: 1) What is the time of switching between primary and secondary PLC in case of failure, using MAX-ON? We have a hump yard process that shoul not be stopped in case of failure in one PLC. 2) What is the overhead in processors due to the use of MAX-ON? Is it significant? Also, we have a program that is scan-critical, so any overhead in processor should be considered. 3) And, finally, in case of using only Cimplicity instead of MAX-ON, there's any way of configure it to hava a float master, i.e., to change the mastership to the processing PLC, not to have it static on only one PLC? It is a important point. Any help will be much appreciated!

[rammin48 1]

It has been a while since I dealt with Max-on so here goes. Switch over time is a function of the amount data that is mapped in the max-on software configuration. Volume Dependent More data = longer time to transfer data. Max-on has no overhead as it is a separate software that creates the files that are part of the code downloaded to the PLC's. Typically the scan time impact is minimal but the network time is again Data dependent and based on the configuration of the amount of data and the rates selected. My recollection is that the code determines the primary. You might be able to set the ladder logic to not switch back to primary. I always treated the GE 9030 series as Primary secondary system. I would test this before trying it tho. I have found the 9030 hot back up system to be finicky to get it set up but works well once completed. Hope this helps you.