The modbus server needs to be enabled via
=>
The modbus server must know what can be accessed from the LOGO!8
To read from the server, the client (or master) modpoll from http://www.modbusdriver.com/modpoll.html can be used (it is not open source and runs under Linux just as 32bit application)
modpoll -m tcp -t1 -r 1 -c 8 -1 192.168.1.<n>
reads one time the discrete Inputs 1 to 8 (I1-I8) from the LOGO!8 (server or slave)
modpoll -m tcp -t0 -r 8193 -c 4 -1 192.168.1.<n>
reads one time the coils 8193 to 8196 (Q1-Q4) from the LOGO!8 (server or slave)
For historical and implementation reasons Modbus addresses must often decremented by 1. On Siemens logo development environment this is not the case.