Siemens SITRANS FC410, Руководство по эксплуатации, Страница: 122 / 160

Modbus holding registers
A.2 Modbus function codes
FC410 with Modbus
120
Operating Instructions, 02/2016, A5E33120874-AC
Response
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
CRC 2 bytes
Example: Set baud rate to 115200 baud (address 529)
Query: 1,16,2,17,0,1,2,0,5,70,210
Slave address = 1 (0x01)
Function = 16 (0x10)
Starting Address Hi, Lo = 2, 17 (0x02,0x11)
Quantity of Registers Hi, Lo = 0, 1 (0x00,0x01)
Byte Count = 2 (0x02)
Registers Value Hi, Lo = 0, 5 (0x00,0x05)
CRC = 70,10 (0x46, 0x0A)
Starting address 0x0211 = 529
Number of registers = 0x0001 = 1
Data 0x0005 = (115200 = value 5)
Response: 1,16,2,17,0,1,80,116
Slave address = 1 (0x01)
Function = 16 (0x10)
Starting Address Hi, Lo = 2, 17 (0x02,0x11)
Quantity of Registers Hi, Lo = 0, 1 (0x00,0x01)
CRC = 80,116 (0x50, 0x74)
Function code 8 (Diagnostics)
Modbus function code 8 provides a series of tests for checking the communication system
between a client (Master) device and a server (Slave).
The following diagnostics functions are supported:
Sub-
function
code
(Dec)
Name Description
00 Return Query Data The data passed in the request data field is to be returned
(looped back) in the response.
10 Clear Counters and
Diagnostic Register
Clears all counters and the diagnostic register. Counters
are also cleared upon power–up.
11 Return Bus Message Count The response data field returns the quantity of messages
that the remote device has detected on the communications
system since its last restart, clear counters execution, or
power–up.