Modbus

[wakho]

How can I test the connection through Labview?

How do I read/write to the device through Labview?

[GerdW]

Hi wakho,

How can I test the connection through Labview?

Send a command and read the device answer. When there is a (correct) answer the communication works…

How do I read/write to the device through Labview?

NI ModBus library comes with example VIs. Start using the "Serial Master" example - and read the device manual to know about the allowed commands…

[wakho]

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GerdW wrote:

How can I test the connection through Labview?

Send a command and read the device answer. When there is a (correct) answer the communication works…

How do I send a command and read the device answer? (forgive me I am new to both labview and modbus).

[NIquist]

Why are you using the NI Distributed System Manager?  Are you reading your instrument across a network?  If not, please just use NI-MAX so there's no confusion about what info you're getting.  If you don't know MAX check the tutorials here:  http://www.ni.com/tutorial/5439/en/   It's a great tool to troubleshoot these kinds of problems.

[GerdW]

Hi wakho,

see the example VIs that come with the NI Modbus installation…

[wakho]

Thank you, your comment was very helpful. So now I can write to the device, no problem. But when i read or query I get this timeout error... How can I resolve this issue?

[RavensFan]

Why are you sending an *IDN? command to a modbus device?  That command does not exist in the modbus protocol?

[GerdW]

Hi wakho,

I really love it when people stick with their threads instead of starting multiple parallel discussions (for the same topic)!

(Yes, sarcasm…)

[Hooovahh]

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@GerdW wrote:

I really love it when people stick with their threads instead of starting multiple parallel discussions (for the same topic)!

(Yes, sarcasm…)

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Or send you PM's asking you how their hardware works.

Did you use the simple serial example I mentioned?  Did you look at the modbus code I mentioned?  Did you take the free training I linked to?  Did you read the hardware manual for the device you are using?

[RavensFan]

Modbus Specifications and Implementation Guides