We are one step closer. Turning on the DTR I can now at least receive the ready byte chr(5) back from the PLC.
However When I do a read or write command nothing happens. I do not get feedback from the PLC on a read and writing commands no longer work and they use to with DTR off.
Also if you have a copy of that code you can send me that would be great but I think I got it with the serial1.ReadExist and putting that in string variable. It?s just that nothing comes back in the serial buffer. See here the results from serial monitor. The working qbasic application is ?ntvdm.exe? and my VBExpress2008 is ?SCADA1.exe? Notice that I am sending the exact same hex code ?in red?. PLC Answers the wakeup 05 but fails to answer the RO00* command. Notice that with the other application in Qbasic ?ntvdm.exe?. It all works. I have tried slowing down with time between write and read with no effect. Any ideas??
Port opened by process "SCADA1.exe" (PID: 2056)
Request: 1/25/2009 04:40:42.54664 (+78.5313 seconds)
05 .
Answer: 1/25/2009 04:40:44.62464 (+2.0781 seconds)
05 .
Request: 1/25/2009 04:40:44.62464 (+0.0000 seconds)
52 4F 30 30 2A 0D RO00*.
Port closed
Port opened by process "ntvdm.exe" (PID: 5412)
05 .
Answer: 1/25/2009 04:41:38.95264 (+0.0156 seconds)
FF 03 AA 05 ?.?.
Request: 1/25/2009 04:41:38.95264 (+0.0000 seconds)
52 4F 30 30 2A 0D RO00*.
Answer: 1/25/2009 04:41:38.96864 (+0.0156 seconds)
52 4F 30 39 2A 0D FF 03 0A RO09*.?..
Port closed