SMC Networks HRR012-A*-20 Series Operation Manual

HRX-OM-W004
Chapter 3 Serial communication
3.10 Checksum calculation method HRR Series
3-10
3.10 Checksum calculation method
3.10.1 LRC(ASCII)
LRC checks the content of the message other than [:] of START and [CR][LF]
of END. The sending side calculates and sets. The receiving side calculates
based on the received message, and compares the calculation result with the
received LRC. The received message is deleted if the calculation result and
received LRC do not match.
Add up the byte number of the message consisting of 8 consecutive bits.
The result except the carry (overflow) is converted to 2’s complement.
 Calculation example
Example) Change circulating fluid set temperature 25.4 ° C
Sending data 0106000B00FE
○Slave Address：No.1
○Function：No.06
○Writing address：000Bh
○Writing data：00Feh
No
Classification
Contents
calculation result
1
LRC message for
calculation
0106000B00FE
-
2
Calculation
Added for each 8Byte
01h＋06h＋00h＋0Bh+00h+FEh=110
h
10h
3
complement of 2
10h→EFh→F0h
F0h（LRC）
4
Sending message
[:]0106000B00FEF0[CR][LF] -
3.10.2 CRC(RTU)
CRC checks the content of the message. The sending side calculates
the data every 2 bytes (16 bits). The receiving side calculates CRC
based on the received message, and compares the calculation result
with the received CRC. The received message is deleted if the
calculated CRC is different from the received CRC.
 Calculation procedure
① Preload “FFFFh” (set 0xFFFF as initial value ).
② Exclusive OR the first byte of the transmitted message with the value in (1).
③ Shift the result of (2) by one bit toward the least significant bit, and fill a zero
into the most significant bit position.
④ If the least significant bit was a 1, exclusive OR the result of (3) with “A001h”.
(Example 1). If the least significant bit was a 0, no exclusive OR takes place.
⑤ Repeat (3) to (5) until eight shifts have been performed.S
⑥ After eight shifts, exclusive OR the result of (5) with the next 1-byte (2nd.
byte).
⑦ The processes (3) to (6) are repeated for all the remaining bytes of the
message.
⑧ The 2-byte data of the result of (7) is the CRC value.

SMC Networks HRR012-A*-20 Series Specifications

General

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