Balluff BSI R11A0-XXR-CXP360-S75G Betriebsanleitung Seite 10

BSI R11A0-XXR-CXP360-S75G
Capacitive uniaxial inclination sensor with Modbus interface
Startup
The sensor has a RS485 interface and is addressed via the
Modbus RTU protocol.
In RTU mode, the beginning of transmission is marked by
a transmission pause at least three characters long. The
length of the transmission pause depends on the transfer
rate.
The slave ID consists of 8 bits that represent the
addresses of recipients.
The slave sends an address back with its answer so that
the master can allocate the response.
The function field consists of 8 bits. If the slave has
correctly received the query from the master, then it
responds with the same function code.
If an error occurred, it changes the function code by
setting the highest value bit in the function field to 1.
The data field (address + quantity/value) contains notes
about which register the slave is to read out, at which
address this begins; it also contains the value that is to be
written into the register.
The slave uses the read out data (e.g. measuring values)
there to send them to the master.
In the case of an error, an error code is transferred there.
The field for the checksum determined by CRC is 16 bits.
The entire telegram has to be transferred in a continuous
data stream. If a transmission interruption occurs between
two characters and lasts more than 1.5 characters, the
telegram has to be evaluated as incomplete and should be
discarded by the recipient.
More information on the Modbus protocol can be found at
http://www.modbus.org/specs.php.
3 english
Structure of the query
The command set consists of a word 8 bytes in length.
Master
Slave ID Function Adress Quantity
Code
1 byte 1 byte 2 bytes
Structure of the response
The answer varies depending on number of queried
registers and is structured as follows:
Slave
Slave ID Function Byte
Code Count
1 byte 1 byte 1 byte
Error indicator
Register Value
address
0 55555 Invalid value in one of the
following registers:
132 = Update time
133 = Number of measurements
134 = Offset from 0° position
See register table
Checksum
/Value
2 bytes 2 bytes
Value Checksum
x bytes 2 bytes
Cause of error