Need to control a serial device with LabView using a GPIB-RS232CT converter

[Hariram96]

Thank you all for taking the time to answer this question.

I am trying to control an Omega CNi32 series temperature controller with Rs232 serial communication enabled using Labview 2009SP1 through a GPIB-RS232CT NI converter

The connection is as follows:

1. From the PC to GPIB-RS232CT NI converter using a USB to GPIB cable

2.  From GPIB-RS232CT NI converter to temperature controller using a DB9 cable

I can successfully control the temperature controller directly from the PC using a serial connection through the DB9 cable, but I need to use the GPIB-RS232 converter module for my application.

GPIB-RS232CT NI converter configuration: G mode with the address set, I can detect the GPIB address but couldn't communicate with the serial device.

The temperature controller is programmed to continuously transmit data and I tried using Visa Read and GPIB Read to get the bytes from the device, but no success.

I have attached the Omega temperature controller and GPIB-RS232CT NI converter manual for reference

[crossrulz]

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@Hariram96 wrote:

The connection is as follows:

1. From the PC to GPIB-RS232CT NI converter using a USB to GPIB cable

2.  From GPIB-RS232CT NI converter to temperature controller using a DB9 cable

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Why?  Just use a USB-RS232 adapter.  Removing parts often simplifies the issues.

[Hariram96]

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@crossrulz wrote:

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Why?  Just use a USB-RS232 adapter.  Removing parts often simplifies the issues.

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You are right. However, my application demands the use of the serial to GPIB converter.

Info about my specific use case: 

I am building a setup with multiple instruments that communicate with a PC using GPIB

The design is to use a single USB port in the PC and connect all the Instruments through GPIB to GPIB cables and one GPIB to USB cable to the PC.

I do understand I can use Mutilport UBS extenders to solve my issue. but I cannot use it for my design. I have to convert the serial device into a GPIB

[Hariram96 · Accepted solution]

I got it to work.

• I tried to communicate with the instrument(the 2nd address indicating the serial device) using Ni max initially but was getting a timeout error message on the read command.
• The reason for the time-out error was due to the byte length I was trying to read
• By default it reads 1028 bytes which were not available and hence the time-out error
• Once I changed the byte size to the desired length I was able to communicate with the instrument without any issue 
• Finally, I used the Visa read-write function to create a Labview Vi

[crossrulz]

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@Hariram96 wrote:

I got it to work.

• I tried to communicate with the instrument(the 2nd address indicating the serial device) using Ni max initially but was getting a timeout error message on the read command.
• The reason for the time-out error was due to the byte length I was trying to read
• By default it reads 1028 bytes which were not available and hence the time-out error
• Once I changed the byte size to the desired length I was able to communicate with the instrument without any issue 
• Finally, I used the Visa read-write function to create a Labview Vi

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Depending on the temperature chamber, you likely just needed to enable the Termination Character and then VISA Read would stop reading when it is read.

[Hariram96]

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@crossrulz wrote:

Depending on the temperature chamber, you likely just needed to enable the Termination Character and then VISA Read would stop reading when it is read.

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That makes sense, Now I understand. Thanks