Hello all,

I'm working on a plant with PCS7 V9.0 SP2. They have an AS with a redundant CPU. Some motor are configured with simocode.

When we make a download in STOP mode (eg. when we create a new connection), we have most of the time (to don't say always) the communication between the speed drive and the CPU down.

The only way to solve it is to pass both CPU in STOP. Download the standby one, then download the master.
When the download is done, the put the CPU standby in RUN mode and, once, the CPU is running, we pass the Master in RUN.

This procedure runs sometimes but not always. 

Does anybody have an idea of the root cause of the problem? In which direction can I search ?

Many thanks,

PP

Have you configured and located the SIMOCODE devices behind a Y-Link or just single sided on one of the controllers?

Are you using any of the SIMOCODE PCS7 libraries or a custom integration?

Behind an Y-link with the library from siemens. 

No customisation

There are 3 supported compatible libraries for PCS7 9.0 SP2.  Which one are you using since you didn't answer?

SIMOCODE pro PCS 7 Library v 9.0 SP2  <  most likely one you are using if its a new plant
<using one of below if plant is old, originates pre-APL>
SIMOCODE pro PCS 7 Library Migration 8.0 SP4
SIMOCODE DP PCS 7 Library Migration (Legacy) 9.0 SP2

If you are not using one of those specific versions you have to do that first.

Now as to your specific problem, some part of what you are saying doesn't make sense.  If you perform HW download in RUN does everything work fine?  With H-system you should be able to make nearly all your changes in RUN, even whatever you mean 'make connections' if that's NetPro just download selected info, not the whole station so no STOP.
So if you download in STOP, it only works if you select the master PLC in the certain order?  Have you validated there are no intermittent communications errors on that Y-Link?