Ccommunicating with Serial Instruments Using GPIB-RS232 converter

[cnoyes23]

I'm new to LabVIEW and I've been tasked with writing a program that records the measurements of an Omega DP41-S strain gage. The setup has a USB plugged into the computer, a GPIB HS plugged into a GPIB-RS232 converter and the strain gage connected to the converter's serial port. Currently, I'm having problems simply communicating with the converter and reading the information stored on the buffer. Does anyone have suggestions on how to use LabVIEW to such a program or on how to communicate with the GPIB-RS232 converter? 

Thanks.

[GerdW]

Hi,

what has this USB to do with your setup?
What do the manuals of your devices say about communication protocol?

[Dennis_Knutson]

You've got a pretty convoluted set-up for simple serial communication. Why have the GPIB-Serial converter instead of a simple and inexpensive USB-Serial converter? Are you using MAX to test communication? What commands are you sending? Is the wiring correct for the serial connection? Can you attach the instrument manual?

[cnoyes23]

GerdW: I may have been a bit confusing with my description. It's just a USB to GPIB cable.

Dennis: I think the set up is needed because the meter itself doesn't have a serial port. It needed an RS232 board installed on it. I'm not sure though. The setup was determined by my boss. I tried to use MAX to send a few commands but even the basic IDN command returns an error message. I believe the wiring is correct since MAX notes the presence of both instruments. Here is the manual for the Omega Strain Gage.  

[RavensFan]

Are you sure you are using a GPIB cable?  Why do you think you would/should be using a GPIB cable?

I've never seen an Omega meter using GPIB.  The manual you attached never mentions GPIB.

So the only way to talk to it is through a serial connection, either RS-232 or RS-485.  But the manual says the serial board is an option for this meter.  Yet you don't seem to know whether you have this option.  If you don't know, how are you connecting the computer to the device?  The wires have to go somewhere!

So do you even know what you have?

[Dennis_Knutson]

You seem to be making a lot of things up. Like sending the IDN command and mentioning a GPIB-Serial converter. Besides not mentioning GPIB, the manual you attached does not mention any serial commands so I have no idea where you are getting the programming information.

This is one of the times that attaching a picture of the hardware would be helpful since you can't describe what you have.

[cnoyes23]

For the project we're working on, my boss wants everything on GPIB. So while it does seem simpler to use a USB to serial cable, he doesn't want that option. For that reason, I'm pretty sure that the serial board option was not used. Instead, the RS232 board was installed so it could connect to the converter. This is a somewhat crude drawing of the setup but it's the best I can do until I go back to the lab Monday.

[Dennis_Knutson]

I would question the boss but that's a moot point.

You have not mentioned the GPIB-Serial device. Is it the one from NI? How did you configure the switches? What command from the instrument manual are you sending? Where is the manual? As I mentioned, IDN is worthless to send and you did not attach a manual that does explain the programming.

[RavensFan]

"I'm pretty sure that the serial board option was not used. Instead, the RS232 board was installed so it could connect to the converter."

So the RS-232 option is not there, but yet somehow it is there?  That sentence does not make sense.

Yes.  Your boss is clueless if he thinks you should complicate things more by throwing a GPIB into the mix.  Perhaps you should throw in a fiber optic cable and a satellite uplink and downlink in the communicaiton path as well.

[cnoyes23]

To be honest with you guys, I don't understand most of these terms or questions. This is the first time I've ever done anything like this. I'm an undergraduate physics student and was offered a lab position by a professor and was then handed this issue. Sorry if I'm saying some nonsensical things. Basically, my boss thinks that I will be able to write a LabVIEW program to communicate with the Omega Force meter. Based on what you've been saying, that seems unlikely. 

Dennis: I sent the IDN query because thats what MAX prompted me to do. Is there a way to communicate with it using VISA? That was the other option I had. I agree that the manual has no serial communication pages in it. The GPIB-RS232 that was ordered is attached below. It is the one from NI and was configured in G Mode. There is a manual in the lab that expands upon the RS232 board and offers some communication tips but I can't find it online. I can post a link for it and a picture of my setup on Monday.

RavensFan: I was confused by serial vs. RS232. Not sure if they're the same. What was installed, per the lab records, was an RS-232/RS-485 Communications board and a 9-pin serial connector for RS-232. This is the exact wording used by my boss to describe the connection system (again not sure whether this makes any sense or not): "Force meter board to RS 232, then RS232 to GPIB-488."