Measure current at NI Switch RS 232 serial port by using a Calibrator connected to the NI Switch through GPIB

[govindsankar]

I have a microcontroller system that is connected to a National Instruments PXI Switch through RS 232 serial port. I need to read the current from this microcontroller system at this com port of NI Switch. This NI Switch is connected to a martel calibrator 3001 using GPIB. I am thinking this calibrator is used to actually measure the value. But how will I program this in LabVIEW. That is current to be measured flows from microcontroller testing system to NI Switch through RS 232 com serial port and this value is measured using Martel Calibrator connected to the NI Switch using GPIB. 

[GerdW]

Hi govindsankar,

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@govindsankar wrote:

This NI Switch is connected to a martel calibrator 3001 using GPIB. I am thinking this calibrator is used to actually measure the value. But how will I program this in LabVIEW. That is current to be measured flows from microcontroller testing system to NI Switch through RS 232 com serial port and this value is measured using Martel Calibrator connected to the NI Switch using GPIB. 

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Ask Martel for a good manual for their calibrator. Then you should know about the commands (and its responses to them) supported by this device…

You want to measure the current flowing over a RS232 communication connection? Really? (Tx line? Rx line? Or both?)

And you connected a calibrator using a GPIB communication to a NI-Switch PXI card? How?

[govindsankar]

If you look at the above pic you will see there are various slots in the NI Switch. Slot 7 is the RS 232 com serial port to which microcontroller system is connected. I believe the NI Switch is the reciever Rx and Microcontroller System is the transmitter Tx. Slot 5 is GPIB to which MARTEL 3001 is connected. So my correct question how can I measure the current in Slot 7 RS232 port of NI Switch by using the Martel 3001 calibrator connected to the GPIB slot of the same NI Switch. PC is connected to the NI Switch in slot 1. 

[govindsankar]

I was wrong, its both Rx and Tx. 

[GerdW]

HI govindsankar,

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@govindsankar wrote:

you will see there are various slots in the NI Switch.

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That is not a "NI Switch", it is a "simple" PXIe chassis!

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@govindsankar wrote:

I believe the NI Switch is the reciever Rx and Microcontroller System is the transmitter Tx.

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The chassis just holds that 4×RS232 card. Rx/Tx are two wires of each RS232 communication cable.

When you "just believe" something you should read about the topic to "really know it"!

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@govindsankar wrote:

So my correct question how can I measure the current in Slot 7 RS232 port of NI Switch by using the Martel 3001 calibrator connected to the GPIB slot of the same NI Switch. PC is connected to the NI Switch in slot 1. 

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This question still doesn't make any sense to me…

Which current on which wire of the RS232 cable do you want to measure? What is the goal behind all this exercise?

(Or do you want to measure the current/power demands of that whole 8431 PXIe card? Why don't you read its manual?)

Again: to learn about the commands and responses of your Martel calibrator you just need to read its manual. Then use VISA functions to setup the communication…

[govindsankar]

I think I got the idea. The input section of the MARTEL 3001 is connected to the PXIe chassis through slot 3 which is switches in rows and columns and current values comes at slot 7 which is the RS232 serial port. So the question is how can I exchange the data from slot 7 to slot 3 of the PXIe chassis. If I get it to slot 3 then I can use the Martel commands to read the value. So do you know how can I do that?

[GerdW]

Hi govindsankar,

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@govindsankar wrote:

I think I got the idea. The input section of the MARTEL 3001 is connected to the PXIe chassis through slot 3 which is switches in rows and columns and current values comes at slot 7 which is the RS232 serial port.

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So the Martel sends some data to your PXIe chassis using a RS232 communication line?

Did I mention you need to read the manual of this Martel calibrator to learn about the communication details?

In the end you use the same VISA functions as you would use for the GPIB communication you mentioned in your previous messages, just with a difference VISA reference…

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@govindsankar wrote:

So the question is how can I exchange the data from slot 7 to slot 3 of the PXIe chassis. If I get it to slot 3 then I can use the Martel commands to read the value.

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This doesn't make any sense to me: why do you want to "exchange data from slot 7 to slot 3"? What exactly do you want to "get to slot 3"???

[govindsankar]

Slot 7 has the current value. If I can get it to slot 3 then I can measure it using MARTEL. MARTEL sends data to PXIe chasis through GPIB. If still my questions are confusing then sorry. I am trying to understand this myself. I am new to instrument control. I just know the basic VISA functions. 

[GerdW]

Hi govindsankar,

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@govindsankar wrote:

Slot 7 has the current value. If I can get it to slot 3 then I can measure it using MARTEL. MARTEL sends data to PXIe chasis through GPIB. If still my questions are confusing then sorry.

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Slot 7 provides some RS232 ports, useful for (digital) communication with an external device. There is no (substantial) current flow, just communication between two computer devices.

Slot 3 contains a matrix switch card, that only can open/close relay contacts. Certainly it does not contain any power supply, be it voltage or current.

I guess you want to have a current flow to your Martel device: where should that current come from?

When you want to measure some current with your Martel calibrator then you need to attach the wire with the to-be-measured current to your Martel directly!

[govindsankar]

Yes by current flow, I mean the digital binary equivalent value. So what I want exactly is the value at the RS232 serial port in PXIe chasis and then get the equivalent current value from that. I dont need to actually measure it with MARTEL calibrator, but I think that is the way to get the value. Send that data from RS232 port of PXIe chassis to MARTEL calibrator. Thats what I thought. So If I am wrong then how can get the value in the RS232 serial port in PXIe chasis programmatically. I just use a VISA configure port and then to it connect the VISA read and then read the value. Is that enough. Will that work?