Rif.: Controlling two or more Eurotherm temperature controller

[usman_o]

Hi all,

I am using 3216 Eurotherm temperature controller which has LabVIEW driver. The provided .vi can be used for monitoring and controlling the controller. However, when i connect two or more similar controller using serial cable, i can only monitor because everytime i tried to change the set point, the LabVIEW hang. Basically i copy paste the existing block diagram and make it double. It works only for monitoring, but not for controlling. I do not know where the wrong is. Please help.

Attached is the vi from Eurotherm and the one i modified for 2 controllers.

Thanks for all your help.

Usman

[pincpanter]

You cannot control both instruments in parallel on a single serial port. You should make sure to query one instrument and afterwards the other.

[usman_o]

I understood what you meant. I sent the query to one instrument then it hangs, even before I was able to send query to the other one. There must be something wrong with the block diagram as it can monitor process value in both instruments

[pincpanter · Accepted solution]

In the standard loop (no setting, no acknowledge), you read process variables by means of oner eading vi. I guess that this reading vi is not set as reentrant - although I cannot verify, because I don't have this vi - , so the two queries are automatically serialized: the program runs one instance of the vi, then the other instance. When you add another query (e.g. the setting), this automatic serialization does not work anymore, since the setting vi and the reading vi can be run at once.

Did you try to serialize the whole sequence?

[usman_o · Accepted solution]

Thanks Paolo,

I understood what you meant and finally i managed to modify the diagram so that it can work for monitoring and controlling more than 2 Eurotherm temperature controller.

[sanvish]

Hi usman/Paolo..

I am also facing same situation, with 35xx eurotherm controller for controlling..when tried to open your file ..its of higher version ..i am currently using labview 2014..can you send me the vi file revised one so it will be helpful.

Thanks&Reagrds

Sanvi