I'm using a Beckhoff BK9000 Modbus coupler to acces some digital i/o.
For now I'm using Modbus poll software http://www.modbustools.com/
Reading digital inputs is working ok and there is no problem with that.
The problem is when I want to write coils 05 for digital outputs. When I try to do the write comand the "module return with errotr" message apears. There are no error leds present on the coupler module. The module is connected to the pc via normal 10/100 switch.
The module was set to the default settings according to the procedure in the manual of the coupler (appears to be working because the digital inputs work). For now the rack cointains only the digital output moduls and the end terminal.
If somebody can help this would be very nice