Manual
Double Sheet Control System R1000 series L20
with integrated fieldbus interface
Communication with the PLC
B0063191 / 1.3
52
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6.4.6 Service "Empty service"
The master initiates the service “Empty service“ with the setting of the service selection. The
content of the index bytes BIN1, BIN2 and the application data bytes 0 to 3 are not relevant. The
checksum of byte 1 through 6 is calculated and inserted in byte 7. To initiate the service the master
switches the handshake bit. In order to avoid data faults the following sequence is mandatory:
1.
Service selection, program index, parameter index, application data byte 0 to 3
2.
Switch handshake
In addition consistent data communication from the master is necessary.
The R1000 checks the data with the checksum and mirrors the index adjustment in BOUT1,
BOUT2 and the application data in BOUT3…BOUT6. A possibly set collision bit is set back. Only in
the last step inserts the R1000 the handshake bit in BOUT0.0 and indicates thereby that the data
has been completely accepted. The same sequence applies here also, in order to avoid data faults.
The slave ensures a consistent data transmission.
Note
If the service “Empty service“ cannot be executed, the collision bit
is set (remains set). In place of the application data a fault code is
transmitted, see section “6.4.8 Reset faulty access“.
6.4.7 Service "Reset parameter channel"
The service “Rest parameter channel“ initiates the master by transferring a zero string. The service
was added for safety reasons during the start-up of the system or in case a fault occurs in the bus.
The R1000 closes the parameters channel and mirrors "parameters channel closed"
(38 00 00 00 00 00 00 00 Hex). The handshake bit remains set to 0. The collision bit is also
set to 0.
Note
If the fieldbus is off-line the service “Reset parameter channel“ is
automatically
executed.
