Endress+Hauser EngyVolt RV12, Operating Instructions Manual

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EngyVolt RV12 Appendix
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Field name Example (Hex)
Starting address High 00
Starting address Low 00
Number of registers High 00
Number of registers Low 02
Byte count 04
Data, High Reg, High Byte 00
Data, High Reg, Low Byte 00
Data, Low Reg, High Byte 00
Data, Low Reg, Low Byte 00
Error check Low F2
Error check High AF
Data must be written in register pairs i.e. the “Starting Address“ and the “Number of
Points” must be even numbers to write a floating point variable. If the “Starting
Address” or the “Number of points” is odd then the query will fall in the middle of a
floating point variable the product will return an error message.
In general only one floating point value can be written per query.
The following response indicates that the write has been successful. But see also
“Exception Response” later.
Field name Example (Hex)
Slave address 01
Function 10
Starting address High 00
Starting address Low 00
Number of registers High 00
Number of registers Low 02
Error check Low 41
Error check High C8
11.4.10 Exception response
If the slave in the “Write Holding Register” example above, did not support that function
then it would have replied with an Exception Response as shown below. The exception
function code is the original function code from the query with the MSB set i.e. it has had
80 hex logically OR'ed with it. The exception code indicates the reason for the exception.
The slave will not respond at all if there is an error with the parity or CRC of the query.
However, if the slave can not process the query then it will respond with an exception. In
this case a code 01, the requested function is not support by this slave.
Field name Example (Hex)
Slave address 01
Function 10 OR 80 = 90
Exception code 01
Error check Low 8D
Error check High C0