Question

I encountered a problem that took me too much time, but without resolving it.soI really want you to help me.

I have an application built with c # wpf, and communicates with ovens via serial port.

the frame I need to send have following form: [EOT] (GID) (UID) (Temp) [ENQ]
gid uid: group identifier and unit identifier (address of the machine).
(eof),(enq) :frames the message.
(temp) means: give me the temperature value.

the only machine that has the same address can answer (master slave architecture).

the form of the response message is: [STX] (Temp) <DATA> [ETX].
the field contain only the temperature value
stx start text. etx end text.

I have no problem with sending and receiving of data, and I can display the value of temperature for a single machine connected.
but when I connect More machines, I do not know which machine has answered the frame that I sent, because the response frame does not have any adress so that I can determine which oven have respond.

So the situation in brief is:
-I send Data to ovens.
– I received data.
– I can not decide which oven answered.
please any one have an idea.
PS: I work with the protocol:EI-BISYNCH of eurotherm EuroTherm

If needed: EI-Bisynch ASCII Sequence Diagrams

Answer 1

In these conditions, the typical solution is:

1. Send the request to the current device
2. Wait for an answer for a defined timeout
   • If we receive an an answer within the timeout, the device responded.
   • If we do not receive an answer, the device is offline, mark it as such.
3. Switch to the next device, goto 1

Basically you should be able to wrap into a loop the code described here:
Providing Asynchronous Serial Port Communication

That is a sample that works with an AutoResetEvent. One of the .Net multithreading that allows synchronizing threads (the threads that sends the request in the loop, and the threads that receive the message in the loop)