Endress+Hauser EngyVolt RV15, Руководство по эксплуатации

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EngyVolt RV15 Appendix
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Protocol RTU protocol. All values stored and returned are in floating point format to IEEE 754 with
the most significant register first.
Read input registers
MODBUS Protocol code 04 reads the contents of the 3X registers.
Example: The following query will request ‘Volts 1’ from an instrument with node address 1:
Field name Example (Hex)
Slave address 01
Function 04
Starting address High 00
Starting address Low 00
Number of points High 00
Number of points Low 02
Error check Low 71
Error check High CB
Data must be requested in register pairs i.e. the “Starting Address“ and the “Number of Points”
must be even numbers to request 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.
The following response returns the contents of Volts 1 as 230.2.
But see also “Exception Response” later.
Field name Example (Hex)
Slave address 01
Function 04
Byte count 04
Data, High Reg, High Byte 43
Data, High Reg, Low Byte 66
Data, Low Reg, High Byte 33
Data, Low Reg, Low Byte 34
Error check Low 1B
Erorr check High 38
11.4.9 Holding registers
Read holding registers
MODBUS Protocol code 03 reads the contents of the 4X registers.
Example: The following query will request the prevailing ‘Demand Time’:
Field name Example (Hex)
Slave address 01
Function 03
Starting address High 00
Starting address Low 00