I was wondering if you could help me with the serial communication between C++ program and micrologix 1500 plc.
I have set the baud 19200, 1 stop bit, no parity, 8 byte size.
In the C++ program, The port opens perfectly.

I do not know wat sort of input does the plc accept? i tried to send an acsii string but the plc would not respond to it.

>>>All i really need is to know what sort of output should i send from my C program as a string that the micrologix 1500 will accept and then respond to...
Also the C+ is a very fast pace language, where as the plc is slower..do i need any special timers or anything?

i have a copy of RSlinks with the RSLogix500, it detects the input/output on the micrologic1500 and i can upload my ladder logic into the micro with no problems.

Your help will be much appreciated.

Please see attached file for the C code..

As was explained at PLCtalk, configure the port for user mode and use the ladder logic instructions designed for interacting with serial devices. OR go to the AB website and download the DF1 protocol specification so that you can talk to the ulogix in system mode. What you are asking for can not be done simply with a writefile statement without some preliminary work.

i have been reading the DF1 file, but its hard to understand. Waht i had understood earlier was to simply send a command to the plc to turn a switch on would be a simple task but it seems thers alot more to it. well im still going tru the DF1. will let ya knw if i need more help. thanks for ur time and comments.