SMC Networks HECR Series Communications Manual

MODBUS communication function
HECR 5-12
5.9 Negative response
A negative response is returned when the following request message is received.
1) When unspecified function code is used.
2) An address out of range is specified.
3) The data field is not normal.
◼ Negative response message (Slave to Master)
1)
2)
Start
Slave Address
Function
Error cODE
LRC
End
[:]
XX
XX
[0]
[3]
XX
XX
XX
XX
[CR]
[LF]
1) Function
Assign the value consisting of the request function code (hexadecimal value) plus 80H in ASCII code.
2) Error Code
Assign error code below.
01：Function code of a command is outside the standard
02：The specified address of register is outside the range.
03：Data field of a command is not normal.
◼ Communication example
1) Slave Address (=Unit number): No 1
2) Read seven consecutive data from register 0100H which is out of range.
Request message
Response message
Code
Contents
Code
Contents
01
Slave Address
01
Slave Address
03
Function
83
Function (03H+80H)
0100
Head address of register out of range
02
Error Code (Specified register address
is out of range.)
0007
Quantity of register to read
7A
LRC
F4
LRC
This product
(Request): 010301000007F4 [CR][LF]
(Response): 0183027A [CR][LF]
Your system
Data is sent and
received in ASCII
code.

SMC Networks HECR Series Specifications

General

Brand	SMC Networks
Model	HECR Series
Category	Chiller
Language	English