Protocol PR2000 is used in devices from the English company Serck. These devices are used mostly for controlling technological processes. The networks utilizing this protocol work typically in the Master – Slave mode.
The terminology is unified from Setr version 22.214.171.124 according next schedule:
PLC Master - CU RADIOSLAVE ... CU RADIOMASTER - Slave PLC
CU (radiomodem) connected via SCC to PLC Master is called
The older Setr uses different terminology, also:
( PLC Master - CU MASTER ... CU SLAVE - Slave PLC )
Data format including example according to point 3.4.
| SYNC1/8 | SYNC2/8 | OS/8 | COUNT+F/16 | BCH1/8 | DATA/8*COUNT |BCH2/16| AA 80 BB 02 00 6C AAAA FEFD
first synchronisation byte
second synchronisation byte
Outstation – address of RADIOMASTER (RADIORELAY)
4th and 5th byte understood together like a Word in Intel
No. of bytes in DATA field (14 bits ; 0 to 5th bit in 5th byte + 8 bits in 4th byte)
2 bit flag located into 5th byte has the following
Bit 6 = 0
check byte via head of packet – first 5 bytes (SYNC1, SYNC2, OS, COUNT, F) counted according to polynomial x8 + x7 + x4 + x3 + x + 1.
actual transmitted data of length COUNT
check Word via DATA, counted 16 bit CRC according to the
It is presumed that external devices will be connected to the CU (e.g. MR400) of the MORSE system through the SCC (serial port).
selecting SYNC1, SYNC2 in the received packet
Check of min. size of packet from SYNC1 (8 bytes), shorter packet is cancelled
Check of ACK flag
Check of BCH1 – if in disagreement packet is cancelled
Check of BCH2 – ditto
Dispatch of data (MORSE packet) to node (typically on RF channel)
ACK Flag = 0 type of MORSE packet USER DATA
ACK Flag = 1 type of MORSE packet PROT DATA
when using packet type PROT DATA a “service Word” is supplemented at the beginning of the data. For ACK Flag = 1 value 0001h. This Word serves only for Morse system and is not accessible to users.
RADIOSLAVE – packet is sent to the address according to OS
RADIOMASTER – packet is sent to the address according to parameter (a): or (A)ut:
SYNC1,SYNC2, OS, COUNT, F, BCH1, BCH2 are supplemented to the received data (MORSE packet) from node (RF channel)
address supplemented to the OS field:
v CU RADIOSLAVE – source from MORSE packet
v CU RADIOMASTER – destination from MORSE packet
packet sent to relevant SCC (serial port)
From the above it is apparent that only service data secured by MORSE system algorithms are transmitted via the (RF) channel. Data on the SC channel is secured by algorithms of the PR2000 protocol.
For reasons of compatibility with networks built from earlier RD300FS radio modems, data is transmitted in mode C92 in the following way (after setting parameter(R)D300FS to ON):
selecting SYNC1, SYNC2 in the received packet
check min. size of packet from SYNC1 (8 bytes), shorter packet is cancelled
“cut-off” SYNC1, SYNC2 from packet
Send packet on RF channel, Morse packet type C92_VAE_DATA (64h)
SYNC1, SYNC2 are added to the beginning of the received data(MORSE packet) from node (RF channel)
the packet is sent to relevant SCC (serial port)
From the above it is obvious that data is transmitted via the RF channel in the way it was delivered to the SC channel, only without SYNC1 and SYNC2, of course secured with MORSE system algorithms.
There is no handshake used on the CU-Serck link- not even SW (via ACK or other characters in the link layer of the protocol) not even HW (only three connections are used – RXD, TXD, GND). In case of overflow of queues of packets for sending to the RF channel (4 packets) there is no way to inform the Serck, and therefore other possible incoming packets are discarded.
SERCK Master ---> CU RADIOSLAVE 690F00AA FFFF AA80 BB02 006C AAAA FEDF FFFF MORSE packet data CU RS AA ---> CU RM BB AAAA CU RADIOMASTER BB ---> SERCK Outstation (Slave) AA80 BB02 006C AAAA FEDF SERCK Slave Outstation ---> RM BB AA80 BB02 006C 6666 AB8A MORSE packet data RM BB ---> RS AA 6666 RS AA ---> SERCK Master AA80 BB02 006C 6666 AB8A
PR2000 parameters: PLC Master - CU RADIOSLAVE ... CU RADIOMASTER - Slave PLC (m):RADIOMASTER (wired to SLAVE) (s)ync word:AA80h (R)D300FS:OFF slave only: (a):AAh (A)ut:OFF (t)imeout:2000ms (q)uit >>
Select Mode (S) RADIOSLAVE (wired to MASTER) (M) RADIOMASTER (wired to SLAVE) (R) RADIORELAY
ATTENTION – The Setr older than 126.96.36.199 uses the reverse labelling M/S !
It is necessary to correctly set the 8 bits mask in the relevant channel at the same time (CNI menu).
Entering SYNC1 and SYNC2 – together a whole Word, typically AA80 (SYNC1 higher byte, SYNC2 lower byte – in terms of Motorola format).
(R)D300FS compatible – switches on communication mode in C92 mode
Next parameters use the RADIOMASTER and RADIORELAY only:
Address of the RADIOSLAVE to which the RADIOMASTER (RADIORELAY) sends data. It only takes into consideration the lowest byte. The remaining bytes of the address are supplemented from its own address on the relevant node.
OFF – RM responses to the address according the parameter (a)
ON – RM responses to RS address, from which the request came. The request must be accomplished it the time shorter then parameter (t)imeout.
(t)imeout – RADIOMASTER waits for the response from PLC Slave for this time