Instrument Control (GPIB, Serial, VISA, IVI)
Read data from 2 serial port and forwarding to single port
Ok, time to take a step back. Please describe in detail the protocol of the message you are trying to read and then pass on. Is it binary data or ASCII? Does it use a termination character? Do you have any control on the protocol used?
@aniketjha wrote:
Sorry I dont understand what does it mean by protocol control.
That was a question of whether or not you had input to what the message format is. Right now it is kind of weird or a serial protocol. They typically do not start and end with the same termination characters. What I am getting at is it would make life a lot easier if you could get those first two bytes removed. From there, I am assuming you are only dealing with ASCII data, so then the termination character is exactly what you want to use (set to 0xD since that is the last byte in the message). If you can manage that, then you just read a line with VISA Read by letting the Termination Character stop the read and you just send the data through the queue when you get data.
But if that is not the case, then it will be a little more interesting to get a single message out. You would need a State Machine of sorts to process the data and then pass it on when you get the full message. States would include reading a single byte looking for the first byte (0D), read a byte and verify it is 0A, and set the termination character to TRUE and read the rest of the message. If a step fails, back to the first.
Hi
In the upper loop you are reading 7 characters.
In the second loop you are reading the number of characters available maybe less or more than 7
In the lower loop you are writing all you read.
I don't think that what you type is what you received and sended.
Can you add indicators in what you receive (both loops separate indicators), the same way as in the lower loop and after running the vi goto edit/make current values default and send that vi again.
Just guessing, you wait in sample 2 300 ms in the upper loop so mixing of parts of the message with loop 2 is quite possible.
That can give errors.
You should reread what crossrulz wrote about protocol.
You now read exactly the number of bytes that is detected but you know it always should be a fixed number! Or wait that number of bytes (calculate that from the baudrate) and read again the number of bytes!
But anyhow don't wait too long or too short.
@aniketjha wrote:
And yes the no. of bytes is not fixed.
Which brings me back to my question: what is the exact protocol of the messages? Something has to tell you how many bytes to read for a message. It could be a message ID, or a length byte, or a termination character.
