Radio, RS232 broadcasting transmission

Someone can help me? I need to connect by RS232 port a radio that the manufacturer of that radio does not define me any protocol, tells me that is sent in broadcast, polling. The issue of polling is clear to me, I realize, but the type of data packet to be delivered to the radio, I do not understand. This is a M340 PLC by Schneider, RS232 Port in Modbus.
Tk's

A radio is a modem that converts from one medium, wired serial, to another medium, wireless, on one end and then re-converts things back again on the other end.

Typically modems do not care about what information they carry, they're just donkeys or mules that carry the load, some kind of data. But with Modbus RTU where there is timing spec, a modem might be designed to handle an entire message at once, or to handshake wirelessly with its partner if a long message meeds to be split and to watch for the timing. The radio modem I used was a store and forward, with a built-in latency period. The time-out on the master had to account for latency (delay) in the messaging.

I discovered that some wireless modems handle either 7 bit data words or 8 bit data words, not both, and RTU uses 8 bit data words.

http://en.wikipedia.org/wiki/Modbus
The above is a link to the Modbus protocol. The packages are just ASCII characters being exchanged.
Here is an article on numbering systems that might help.
http://accautomation.ca/what-everybody-ought-to-know-about-plc-programmable-logic-controller-numbering-systems/

Regards,
Garry
http://www.accautomation.ca

Hello, thk's for help.
The problem is not the PLC, or what is a PLC or, what is a protocol, please.
It is only, which the serial port radio will recognize, if not know what I'm sending?
I supose that Danw, have some reason, thank you.