Table 6: Function Codes Supported By Sec 3120 - Sensor Electronics SEC Millenium Series Instruction And Operation Manual

Implemented Functions and Registers Defined
The function code identifies the command being issued to the device. It is one
byte in length and has a value of 1, 3, 5, 6, 15 or 16.

Table 6: Function Codes Supported By SEC 3120

Function Code
1
3
5
6
15
16
For the current 16-bit version, registers are only mapped for function codes 3, 6,
and 16. Otherwise an exception response will be generated.
In most cases, there is no response for a query that contains an invalid slave
address, invalid CRC data or a non-supported broadcast mode, etc. In some cases, the
unit might issue an Exception 2 as an error response if an invalid register address is
requested for a valid function code. However, if invalid function code is issued, such as
function 07 were transmitted, then an Exception 1 message would be generated to
indicate that the function code is not supported.
Query Coil Status Message
Field Name
Slave Address
Function Code
Address High
Address Low
Num Points High
Num Points Low
CRC Low Byte
CRC High Byte
SEC 3120 16-bit Modbus Manual
For Version 1.2 and above
Read Coil Status Registers (not supported)
Read Holding Registers
Force Single Coil Register (not supported)
Preset Single Holding Register
Force Multiple Coil Registers (not supported)
Preset Multiple Holding Registers
Example (Hex)
01
03
01
5B
00
03
75
E4
Page 25 Of 46
December 2012
Description
Response Exception 2
Field Name Example (Hex)
Slave Address
Function Code
Exception Code
CRC Low Byte
CRC High Byte
Sensor Electronics Corporation
P/N 1580282, Rev. 1, 20121228
01
83
02
C0
F1