serial port communication with TESA(TT20)

[Chatur]

Tesa TT20 has buad rate:4800, start bit:1., data bit:7, stop bit:2,parity:even with OPTO_RS input/output hard ware.

[Dennis_Knutson]

What kind of help are you asking for? How to configure the serial port in LabVIEW, commands for the instrument, cabling?

[Chatur]

My respect and thanks to Denis Knutson,
sir, I have already communicated with TT20 in visual basic. In labview I have used the VISA tools, I have configure and put the command but data is not received. There is a button,for serial commu on the instrument Pressing which PC is reading the data. Otherwise it is only running but data automatically is not coming. What may be wrong."

[Dennis_Knutson]

If you're using one of the shipping examples (LabVIEW <-> Serial or Serial Communication.vi), you might only need to add a termination character to the write string. Most serial devices require one (like a carraige return or end of line) and the examples don't include this. The simplest way to add a termination character is to use the concatenate strings function. Wire the write string to the first input and the correct termination character to the second input. Wire the output to the VISA write function. String constants can be found on the String palette. If that's not the problem, could you explain a little more which VISA functions you're using or post the code so that we can have a look at it?

[Chatur]

I have got the data.It needed a termination character which I was giving in command itself.It works in step mode, not in run mode, may be a wait is needed, but where and how. Secondly for a single set of thichness reading I have to write and read twice. It has to go along the length of sample(rod) measuring its thickness in micron and storing and displaying the each reading. Please suggest.
Thank you very much.

[Dennis_Knutson]

It's possible that you need a wait after you do the serial write to give the instrument time to do a measurement and place the result in the buffer. There's a couple ways to do this. One is to just put a fixed wait after the serial write and then read the number of bytes expected. You can use the Wait + (ms) function on the Data Acquisition>Counter>intermediate counter palette. It worsk like the normal Wait (ms) function excpet it has error in/error out connections that you can use for dataflow. You can also setup your read to stop when a termination character is received. You set this up with the VISA Configure Serial Port function.

Serial communication can be a real pain and I would recomend that you also look over so
me of the extensive information on the NI Developer Zone. One place to start is the turorial here.