SMC Networks HRR012-A*-20 Series Operation Manual

HRX-OM-W004
Chapter 3 Serial communication
HRR Series 3.9 Function codes
3-9
2)
RTU mode frame
RTU mode starts from and ends with at least 3.5 characters of silent interval. Silent interval
is indicated by T1-T2-T3-T4.
Table 3.8.2 RTU mode message frame
a)Start
b)Slave
Address
c)Function d)Data
e) Checksum
(CRC)
f)End
T1-T2-T3-T4 XX XX XX
～
XX XX XX T1-T2-T3-T4
a) Start
In Modbus RTU mode, message frames are separated by a silent interval
(non-communication time). At least 3.5 characters of silent interval are necessary at the
beginning and the end of the communication frame.
b) Slave Address
This is a number to identify this product. “1" is the default setting. This can be changed by
the operation display panel.
c) Function
Command is assigned.
d) Data
Depending on the function, the address and the number of the register, the value of
reading/writing are assigned.
e) CRC
CRC
method.
Refer to”3.10.2 CRC(RTU)”.
f )End
3.5 characters of silent interval indicates the end of a message.
3.9 Function codes
Table 3.9-1 shows function codes to read or write register. Refer to "3.11
Explanation of function codes ".
Table 3.9-1 Function codes
NO Code Name Function
1 04(04h) read holding registers
Reading multiple registers
2 06(06h) preset single register Writing registers
∗
1
3 16(10h) preset multiple registers
Writing multiple registers
4 23(17h) read/write 4x registers
Reading/writing multiple registers
∗1：Broadcast is not supported.

SMC Networks HRR012-A*-20 Series Specifications

General

Brand	SMC Networks
Model	HRR012-A*-20 Series
Category	Chiller
Language	English