Siemens FCT010/DSL, Руководство по эксплуатации, Страница: 153 / 180

Function code 16 (Write multiple registers)
General exceptions
• Writing less than 1 or more than 16 registers => Exception 3 (Illegal data value)
• If ByteCount is not exactly 2 times NoOfRegisters => Exception 3 (Illegal data value)
• Requesting invalid start address or start address with invalid quantity => Exception 2 (Illegal
data address)
Application exceptions:
• Application errors; min/max limit of parameter exceeded; or parameter write-protected =>
Exception 4 (Slave device error)
• Application errors include writing to ReadOnly holding registers
Holes/register alignment:
• If start-address is not the start of a mapped holding register => Exception 2 (Illegal data
address)
• Writing to holes is allowed (ie ignored - and no exception occurs) - except for the condition
described above
• If the end address is only part of a mapped holding register item (e.g. one half of a float
value), the action depends on the data type. Writing parts of all data types => Exception 4
(Slave device error)
Function code 16 example
Query
Slave address 1 byte
Function 1 byte
Starting Address Hi 1 byte
Starting Address Lo 1 byte
Quantity of Registers Hi 1 byte
Quantity of Registers Lo 1 byte
Byte Count 1 byte
Registers Value Hi 1 byte
Registers Value Lo 1 byte
: :
Registers Value Hi 1 byte
Registers Value Lo 1 byte
CRC 2 bytes
Response
Slave address 1 byte
Function 1 byte
Starting Address Hi 1 byte
Modbus communication FCT010
C.2 Modbus function codes
SITRANS MASS 2100 & FC300 (FCT010/DSL)
Operating Instructions, 06/2020, A5E39788682-AB
153