Specifications

1070 072 131-102 (96.08) GB
BUEP64 Protocol9-4
The 3964R protocol is best divided into two levels.
Interpreter
The Interpreter manages the data exchange, and processes and monitors
the centralised or decentralised jobs. It establishes a connection with the
PLC, processes the data and ensures that data is transferred in blocks.
The Interpreter recognises faults and signals a defective or fault-free data
exchange to the PLC.
The Interpreter calls up the Transfer Routine with all data required for its
functioning.
Transfer Routine
The Transfer Routine handles the actual acknowledgement interchange
on the line. Once initiated by the Interpreter, the Transfer Routine com-
pletes the transfer automatically
If transfer faults occur, the defective block is repeated. The Transfer Rou-
tine signals a fault-free and/or defective data exchange to the Interpreter.
To facilitate understanding of the description of the following sequences,
the abbreviations used therein are briefly explained:
RST = Requesting station
PST = Peripheral station
STX = Start of Text, control character for initiating the data transfer.
ETB = End of Block, control character
ETX = End of Text, control character
BCC = Block Check Character" block check character, checksum of the trans-
ferred data.
DLE = Data Link Escape, control character.
NOTE – If this identifier occurs as useful data,
it is transmitted a second time ==> DLE doubling.
DLE doubling is included in the checksum.
CDT = Character Delay Time, maximum time between two characters. This
time is monitored by the receive device (220 ms).
ADT = Acknowledgement Delay Time, maximum time up to confirmation of a
control character.
ADT depends on the protocol:
3964 -> 550 ms
3964R -> 2000 ms
RDT = Response Delay Time, maximum time up to the start of a response
message or transfer completion sequence (5 - 20 seconds, depending
on the baud rate ).