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BVS ID-M1280xF1-xx-xxx
4.3.4.1 Toggle mechanism
If more data is to be transferred with a command or with a response than is available in the input / output buffer,
a toggle mechanism is used. This means that further data is transferred sequentially in further PLC cycles.
This only concerns the commands
•
Query results (0x03) and
•
Set reference values (0x04)
NOTE
If toggling is not required, the toggle bits TI (PLC) and TO (BVS ID) remain at 0 and are not considered!
For signaling purposes, the following are used during transmission
•
PLC → BVS BVS ID - the TI-bit (Toggle-In) in the output buffer
•
BVS ID → PLC - the TO-bit (Toggle-Out) in the input buffer is
used.
Before and after the end of a communication cycle between PLC and BVS ID the TI-bit must be 0. The BVS ID
automatically also always sets the TO-signal to 0 after a communication.
1.
PLC writes in the output buffer: command identifier, data length and the first part of the data. (The data
length is the length of the total data to be transmitted).
2.
PLC deletes TI (if still set).
3.
PLC sets.
4.
BVS ID reads command ID, data length and (partial) data and recognizes from the data length and size
of the cyclic buffer that further exchange cycles are necessary.
5.
BVS ID sets Job Start and TO.
6.
PLC recognizes the change of state of the TO and writes the next partial data into the output buffer.
7.
PLC inverts TI.
8.
BVS ID recognizes the inverted TI and reads the next partial data.
9.
BVS ID inverted TO.
10.
If further partial data are to be transferred, proceed with 6. When all data have been transferred, proceed
with 11.
11.
BVS ID set Job End.
12.
PLC reads command status, data length and (partial) data.
13.
PLC deletes Job.
14.
PLC deletes TI.
15.
BVS ID deletes Job End, Job Start and TO.
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