Specifications

9. UNI protocol

UNI is the "Universal" protocol utility designed by RACOM. It is not a new SCADA protocol, it can actually

process different protocols of different vendors. It supports both the standard MASTER -SLAVE and

the MULTI MASTER types of communication. At least one Master is required in the network.

The SCADA protocol to be handled by the UNI has to meet solely the following condition: There has

to be an 8 or 16 bit* protocol address in every message generated by a Master station and the address

position in all messages has to be the same. The position of address in the reply from an RTU is not

relevant, because the reply is always send back to the address where the request originated.

Note

Some SCADA protocols use two byte ASCII address, which is an ASCII representation of

an 8 bit address in the hexadecimal format (e.g. "8C" means 8-bit value 0x8C in hex / 140

in decimal notation).

Address bytes for some protocols:

3rd BytePR2000

2nd ByteRDS

8th Byte (without local ACK)Mars-A

2nd ByteHirsch

9.1. MASTER – SLAVE communication

Master reads the address byte defined by configuration and generates the destination IP address using

the mask or the translation table. The message is then delivered to that IP address and the respective

UDP port (e.g. the port No 8882 which is assigned to the COM2 interface).

An example of Master configuration is in the picture above. The address translation then proceeds as

follows:

UNI protocol