RACOM RipEX - Page 157

The 3964 protocol is utilized by the Siemens Company as a Point-to-Point connection between two
controllers. Meanwhile it has developed into an industry standard that can be found on many devices
as a universal communications interface. 3964R is the same as 3964, in addition it only uses BCC
(Block Check Character). 3964(R) handles only the link layer (L2 in OSI model), hence RipEX uses
a similar way to read "SCADA address" as in UNI protocol.
There is a handshake STX(0x02) – DLE(Ox10) on the start of communication and DLE+ETX – DLE
on the end. This handshake is performed by RipEX locally, it is not transferred over the RipEX
network.
Communication goes as follows:
LocalRTU -> STX -> LocalRipex
LocalRipex -> DLE -> LocalRTU
LocalRTU -> DATA+DLE+ETX+BCC -> LocalRipex
LocalRipex -> DATA -> RemoteRipex*
LocalRipex -> DLE -> LocalRTU
RemoteRipex -> STX -> RemoteRTU
RemoteRTU -> DLE -> RemoteRipex
RemoteRipex -> DATA+DLE+ETX+BCC -> RemoteRTU
RemoteRTU -> DLE -> RemoteRipex
* only this packet is transferred over the RipEX network, all the other ones are handled locally.
Italicised parameters are described in Common parameters.
Mode of Connected device
Master
Address mode
List box: Binary (1 B), Binary (2B LSB first). Binary (2B MSB first).
Default = Binary (1 B)
RipEX reads the Protocol address in the format and length set (in Bytes).
Address position
Specify the sequence number of the byte, where the Protocol address starts.
NOTE 1: 3964(R) protocol is using escape sequence (control sequence) for DLE(0x10).
I.e. when 0x10 is in user data, 0x1010 is sent instead. When address position is calculated,
the bytes added by escape sequence algorithm are not taken into account.
NOTE 2: The first byte in the packet has the sequence number 1, not 0.
Broadcast
Address translation
Table
Mask
Slave
Broadcast accept
DLE timeout [ms]
Default = 1000 (min. 300, max. 8190)
RipEX expects a response (DLE) from the connected device (RTU) within the set timeout.
If it is not received, RipEX repeats the frame according to the "Retries" setting.
157© RACOM s.r.o. – RipEX Radio modem & Router
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