Foe sure, you have different modes of operation for your instrument, the one is perhaps default that it outputs the information continously. Maybe you shoild configure it to use query/response, with this kind of communication, you are sure that you will capture each whole telegram.

If in case you will process the received message and start receive in the middle of transmitting of new message, you will loose the first part of it. Therefore the best way to make it reliable you should use a sequence like:

1. start receive

2. send query

3. wait until receive done

4. parse received message

5. go to step 1.

subin

Sir,

As you mentioned i too find missing in characters sometimes when i try just to read contonuously from the weighing controller. i saw it was because the data may filled in receive buffer wrong order.

So i the device configurattion of port i select the option "Recoganize message start with a character sequnse." As in my case i get my data start with characters W,T so i look for this characters receive mssage configuration.

I have already tired the option which i send a query by using SEND_PTP and try to get the data using RCV_PTP. but in SEND_PTP i just get a hex value 7000.

I feel i can use send and receive ptp functions with my CB1241 in 2 wire.as data will wait in buffer.

There should be some setting to make sure never Tx and Rx get disturbed.

I tried to get some sample programs i just see some samples just using either one SEND_PTP or other just using only one RCV_PTP. couldnt find one PLC program with both SEND_PTP and RCV_PTP.

7000hex for send_ptp means its not busy, it is normal because the message at high baudrate is sent immediately, you won't see it in the monitor

The setting is done with correct program algorithm by checking status of both functions rcv/send.

First you need to know if the recieve or transmit are busy, when its idle it means that receive has finished and something is in the buffer. If NDR is high, then valid data are in the buffer, at no matter of validity you can sendcommand query again.

You can also try with start chars, but more important are the timeouts at end characters. With timeaouts you can set up such that RCV_PTP will stop receiving if message takes to long, comm is disconnected, or normaly when message will arrive and your instrument ends transmittion.

In all cases the send command will be issued automaticly, thus repeating without any special program in plc.

In attachementis my idea, don't know if it works.