shared applications between PM861 PM864 in 6.0.1
I have a PM861 controller that shares applications and tasks with a larger capacity PM864 controller, but the PM861 is the one with the highest logical load that hosts two applications and has the largest number of connected modules. the system is in 6.0.1 version.
my questions are, what kind of problems can appear with shared aplications? what recommendations are there for using shared applications?
for the other side, i have problems with modules DO820, all the DO820 modules connected by opical modulebus with active channels (only affected channels that were active), they changed state intermittently (Every 1 sec, the output went "off" for approx. 0.2 seconds and then returned to "on"), being that by logic these outputs had to remain active.
Sharing application/POU between the controller is not recommended, always use separate application with program with separate scan for each type of controller based on ur needs.
If u share programs between controllers then off course application complie take place in both controller and leads to task congestion and hence increase in load.
Use EAC to exchange communication between controllers
I have only made one major project where applications were shared between multiple controllers. It is not something I would repeat without very good reason.
It is easy to write programs that must share some IO in different controllers. Eg, our customer had all the analog IO in one locations and all the digital IO in another - So controllers were placed in each location. You do not have to think about how to communicated between controllers, because eerything just happens automaticaly.
Its easy to completely xxxx up your application by having your IO in the wrong controller and not realize this until it is too late. - Even though I/O is shared it is still "owned" by a controller. So, if the output channel is connected to controller A, it is owned by controller A and only Controller A can write to that channel, so you have to break up your programs by controller anyway.
Sharing an application across two controllers can solve some problems where a small amount if IO exists in the "wrong" controller. But the more IO you have, the more complicated things become.
If you have a PM861 and a PM864, then everything wil fit in a single PM891. My recommendation would be to combine everything into a single controler.