Problem communicating to equipment via serial port using VB

Question

0.00/5 (No votes)

See more:

I am trying to communicate with an equipment (SR780 from SRS) using serial port, in Visual basic (VB). I can send (write) but am not able to read. However, I can write and read using hyperterminal without any problem.

Using the same VB code, and the same computer, I am able to communicate with another instrument (QCM200, from the same company) via serial port. Hyperterminal also works fine with this instrument. I am not able to figure out what can go wrong.

I am using Windows 7, 64 bit. Visual Studio community edition 2013. .Net 4.6.

Any help is appreciated.

Best Regards
S. Ramanathan

What I have tried:

I am using readline and am getting a timeout error. Increasing the weight time doesn't help

I tried using readto(vbLf),then replaced vbLF with vbCr, then with vbCrLf and none of them help.

Posted 4-Jun-16 5:50am

Member 12565464

Updated 4-Jun-16 15:57pm

Add a Solution

Comments

Richard MacCutchan 4-Jun-16 12:03pm

Most issues with serial ports are due to the nature of the device or its connection. You should check with the manufacturer to see if they provide any SDK/API or documentation for the correct access methods.

Sergey Alexandrovich Kryukov 4-Jun-16 13:58pm

What kind of help would you expect, without a single line of code shown? And even if you did that, how would we know if all the settings match the device's requirements? Just check up all thoroughly, compare with hyperterminal settings which work...
—SA

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

George Jonsson · Answer 1 · 2016-06-04T15:57:00

As it is an instrument I presume you want to send a SCPI command and then read the response within a short time.

For SerialPort.ReadLine to work, the response must contain a termination character equal to the one set by the property SerialPort.NewLine (default is Line Feed).
So read the documentation and check what termination character the instrument is using.

Or it could be that the instrument is expecting as specific termination character to process a command.
Same thing, read the communication.
If the instrument accepts the command sent, you can also check by sending a command that is visibly detectable on the instrument, such as turning off the display or something similar.

When dealing with serial port communication, there is a nice tool called PortMon.
PortMon will monitor everything that is happening on the serial port and is very useful in this kind of situations.
It is a free tool and you can download it here: Portmon for Windows[^]

Using PortMon you can compare what data is sent when you are using HyperTerminal (and it works) with your own application (and it doesn't work).