Specifications

1070 072 131-102 (96.08) GB
BUEP64 Protocol9-6
9.4 SEND Connection Sequence
The requesting station (RST) transmits the STX control character to esta-
blish the connection.
If the peripheral station (PST) responds before the acknowledgement
delay time elapses with the DLE character, the RST switches over to
Transmit Mode.
If the PST responds with the NAK character, with any other character, or
if the acknowledgement delay time (ADT) elapses without any response,
the connection setup fails.
After a total of three unsuccessful attempts, the procedure is terminated
and a fault is signalled to the PLC.
If the connection setup is successful, the data is transmitted to the peri-
pheral device. The peripheral monitors the intervals between the incoming
characters.
The interval between two characters must not be more than the character
delay time (CDT = 220 ms).
When the transmission is complete, the Transfer Routine adds the DLE,
ETX and BCC characters as an end identifier and waits for an acknow-
ledgement character. If the peripheral transmits the DLE character within
the acknowledgement delay time ADT, the data block has been accepted
fault-free. If the response was NAK, any other character, or if the time
elapses without any response, the transmission is repeated. After a total
of three unsuccessful attempts, the procedure is terminated and a fault is
signalled to the PLC.
If the peripheral transmits the NAK character during a routine transfer, the
current block is terminated and is repeated according to the abovemen-
tioned procedure
Up to 128 user data bytes can be transferred per message.
If a DLE occurs in the form of useful data, DLE is doubled.
Larger volumes of useful data are transferred in the form of one or more
transfer completion sequences.