Chino LT830 Series, Instructions Manual

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(Table 2. Function code table)
Code Functions Unit MODBUS original functions (ref.)
01 Read digital (ON/OFF) parameter 1 bit Read coil status
02 Read digital input data 1 bit Read input relay status
03 Read analog parameter 16 bit Read hold register contents
04 Read analog input data 16 bit Read input register contents
05 Write digital parameter 1 bit Change single coil status
06 Write analog parameter 16 bit Write into single hold register
08 Send received data (for diagnosis) Loop-back test
15 Write two or more digital parameters Change multiple coils status
16 Write two or more analog parameters Write into multiple hold registers
6.3.3 Data section
Data configurations depend on the function codes. A master request consists of the code number of
the data to be read or written (Relative No. to be calculated from the Reference No. described below)
and the number of data pieces. Response from slave units consists of data responsive to the request.
Every MODBUS basic data consists of 16-bit integers, with or without codes depending on individual
data. It is thus configured as integers with their decimal places assigned to separate addresses, or
normalized with the upper and lower limits specified by the scale with fixed decimal places. The LT830
controllers employ the system of assigning the decimal places to separate addresses.
6.3.4 Reference Nos.
Data in the LT830 controllers have “Reference No. ” assigned to each of them which is required for
reading and writing the data. The data in the LT830 controllers are classified into “Digital parameter”,
“Digital input data”, “Analog input data”, “Analog parameter” depending on their type. The Nos. In the
message are designated by the “Relative Nos. ” corresponding to the Reference Nos.
(Table 3. Reference Nos. and Relative Nos.)
Data type Reference No. Relative No. MODBUS original (for reference)
Digital parameter 1 to 10000 Reference No. – 1 Coil
Digital input data 10001 to 20000 Reference No. – 10001 Input relay
Analog input data 30001 to 40000 Reference No. – 30001 Input register
Analog parameter 40001 to 50000 Reference No. – 40001 Hold register
Example) “The Relative No” of the measured value (PV) at “Reference No. 30101” is “100”.