Instrument Control (GPIB, Serial, VISA, IVI)

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Reading the output buffer of a VISA instrument ONLY

Hello Community,

 

I'm working on reading a Watlow F4 temp controller

 

Background details:

The watlow's RS-232 port is connected to a serial to ethernet device that connects to the main network PC that has a running labview program to constantly monitor the watlow

This main PC sends commands to the watlow and reads all key information such as temp, profile name, status, set points, alarms, etc etc. 

This part is fully functional and works no problem.

 

Next step:
I need to add a local PC (it can't be connected to the network due to multiple constraints on how our network is setup) next to the chamber that the watlow is controlling, that I can create my own program to do different tasks according the the information thats being retreived on the watlow. 

 

My plan:

I recently purchased an rs232 cable splitter. The rs232 signal coming out from the watlow will be split, one end going to the main server controlled by the main network PC, and the other end going to my local PC. 

The problem is if I run my program on the local PC, it works, but it leaves an error on the main network PC (i'm assuming because we can't transmit commands to the watlow from 2 different devices). 

Now if I shut off my program on the local PC, the main network PC's program will resume normal function, error free. 

 

What I need help on:

Is it possible for me to just read the output buffer ONLY on my local PC's labview program? that way I can still retrieve key information from the watlow, but not transmit any commands?

It's MODBUS RTU that the main network PC uses to send commands to the watlow controller.

 

Am I correct in my assumption that I can perform read on the "recieve" line from the rs232, on multiple PCs, but only one PC can utilize the "transmit" line? 

 

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Bpatel wrote:

Am I correct in my assumption that I can perform read on the "recieve" line from the rs232, on multiple PCs, but only one PC can utilize the "transmit" line?


I believe that is correct.  But you will actually need 2 serial ports in able to figure out what the data is.  One port to read the data being sent by the network PC and the second for the transmit of the Watlow controller.


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