- Radio-Tech Limited User Manual Radio Modems

16
OPERATION
The RTcom protocol permits 100% transparent operation and direct cable emulation. Simply what goes in comes
out! R.F. packet framing, code balancing, encryption and preambles etc are taken care of automatically within the
modem.
Standard industrial communications protocols such as Modbus include a secure CRC 16 or 32 error check code on
data transfers and will probably already be in use over your link, particularly if you are linking PLC's. Rather than
duplicate the CRC and risk increasing the overall bit error rate the RTcom protocol leaves your protocol 100% intact
and does not add any further error checking and subsequent time delay to your messages.
LED's
Status LED's are provided to aid use. On the Global, Universal and Max, the top, green LED indicates
power and the CPU status. If all is well this LED will blink at a regular interval.
The centre amber LED is for received data communications (message received or sent to the data
terminal) by cable.
The bottom red LED indicates the transmission of data.
All LED's Blink
If all LED's should blink together this indicates a data configuration error. This is normally caused by the
data rate, parity etc being incorrect at the transmitting end. The data configuration error mode is
normally triggered by the occurrence of a framing error.
Manual intervention, i.e. changing the dip switches and/or the data terminal will be required. Note both
ends of the link must share the same configuration.
Only after pressing and releasing the reset button will the configuration become effective.