Modbus Server

Modbus Server
	Chapter 8. Modbus

The modbus server needs to be enabled via Tools => Ethernet Connections

Figure 8.1. Modbus Server

The modbus server must know what can be accessed from the LOGO!8

Figure 8.2. Modbus Server addresses

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)

Important

For historical and implementation reasons Modbus addresses must often decremented by 1. On Siemens logo development environment this is not the case.