Jared Henley - 2012-04-05

Hi everyone,

I'm trying to work out why I don't get any connection to my PLC.  I've never used libnodave before so I have very little idea of what success looks like.

First, the gear I'm using:

* S7-200 CPU, address 2 (default), baud rate 19200
* 3rd party USB<->PPI adapter, maximum PPI speed 19200 (FWIW the install CD has DJGX and a lot of chinese writing on it)
* Linux
* libnodave 0.8.4.6

The USB<->PPI adapter presents itself as a serial port to the PC.  On my system it shows up as /dev/ttyUSB0.
Permissions are correctly set for me to read and write to that port.  I have proved this adapter to communicate with the PLC using Siemens own software under Windows.  But it can't support 187.5kbaud, only 9600 and 19200.

Running testPPI results in the following: 

$ ./testPPI /dev/ttyUSB0
timeout in _daveExchangePPI!
Trying to read 64 bytes (32 words) from data block 1.
 This is V memory of the 200.
Press return to continue.
timeout in _daveExchangePPI!
Trying to read 16 bytes from FW0.
Press return to continue.
timeout in _daveExchangePPI!

I have experimented with altering the data rates in testPPI.c and recompiling, with the same results.  In particular, I've set the serial port data rate and daveSpeed to 19200 and daveSpeed19k respectively.  I've changed from even to odd parity and back.

The Tx LED on the adapter flashes while testPPI tries to communicate, but the Rx LED is always dark.

Any suggestions?