Balluff BVS ID-M1280-F1 Series, Configuration Manual

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BVS ID-M1280xF1-xx-xxx
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4.3 IO-Link / Fieldbus Process Data Protocol
4.3.1 Introduction
Two buffers are needed to exchange data and commands between BVS ID and the fieldbus controller (input
buffer and output buffer). The buffer contents are exchanged using cyclical polling. When writing to the buffer,
the transmitted data from the previous cycle is overwritten. If some bytes are not being used in a cycle, then
they retain the last value.
Most of the commands are executed as command-response pair via a handshake mechanism. The PLC
"sends" a command to the
BVS ID and the BVS ID "responds" with a result. This process is synchronized with
3 bits in the cyclical memory and referred to as handshake. The handshake bits are called Job bit and Job End
bit.
4.3.2 Handshake mechanism
Basic sequence of the PLC data exchange
The PLC sets command ID, data length and data in the output buffer and then the Job bit.
The Job bit tells BVS ID that a job is being transferred and the data to be transmitted are valid.
BVS ID accepts the command, executes it, and sets the Job Start bit.
BVS ID correctly executed the command and sets command status, data length and data in the input
buffer and then the Job End bit.
The PLC sees the Job End bit, reads the data from BVS ID and then resets the Job bit.
BVS ID sees the reset Job bit and resets the Job End and Job Start bit. BVS ID is ready for the next
command.
Please note the double bit string chapter in "Process Data Buffer".
NOTE
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