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PCOM via Radio Modem


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Hello All

We are trying to use the PCOM - Protokoll via Radio Modems ( Satel 3ASd ).

To find the correct route, these Modems have the ability to detect ( independent of the used protokoll ) the Node - Number ( Unit ID ) of the destination PLC.

For this, the Offset and Length of the Node in the Frame have to be configured.

So, for PCOM - ASCII, Offset 1 and Length 2 must be configured and everything works fine !

For PCOM - Binary, Offset 6 and Length 1 must be configured and here is our problem:

Visilogic uses both ( ASCII and Binary ) Protokolltypes so this setting in the Radio Modem does not work and we are unable to make any program changes or debugging via the Radio Links !

One idea was to modify the PCOM - Frame by adding the Unit ID ( to have a fixed position for both types ) before the STX of the real Frame:

For Example Unit ID 01:

ASCII - Frame: '0','1','/','0','1',......,<CR>

Binary - Frame: '0','1','/','_','O','P','L','C',....,'\'

The result was, that there was no response from the PLC so it looks like the PLC does not synchronize to the STX and ignore the additional leading charactes !

I hope somebody has an idea how to solve this problem !


we are talking about more than 300 ( ! ) Stations connected over 4 different Radio Frequencies !


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