OHM ELECTRIC COOL CABI OCA-H300BC-AW2 Instruction Manual page 52

8- Communication method
Communication starts from a request message from the customer's equipment Master and ends with a response
message from the cooling unit Slave . The cooling unit does not send a request message.
Message configuration
① Slave address byte
Slave address
①
Communication address for COOLCABI Slave . The value is set by the parameter Ad
unction code
②
This is a code to specify the function which is desired to be executed by COOLCABI Slave . The codes 3, 6
and 6 are used.
Data division
③
Data to execute the function code. The structure of data division differs by function code.
Error check
④
CRC is a -byte
Load the register of
Calculate the exclusive OR of lower bytes of the CRC register and the first 8 bits of the message, and then
put the result in CRC register.
3 Shift the CRC register one bit to the right least significant bit direction to set the most significant bit to
.Check the carry flag.
4 When the carry flag is , the above step 3 is repeated Shift the CRC register again .
When the carry flag is , calculate the exclusive OR of the generator polynomial xA
and the CRC register.
5 Repeat the above steps 3 and 4 until the bit shift becomes 8 times. This operation processes 8 bits.
6 Repeat the above steps from
are processed.
7 The last value of the CRC register is the CRC value.
8 When storing CRC values in a message, the values are stored in the order from lower-order 8 bits to higher-
order 8 bits.
Request message and Response message
①Reading of multiple registers
Request from the customer device Master
COOLCABI Slave address
unction code
Register number
Number of read register
CRC
②Writing to a single register
Request from the customer device Master
COOLCABI Slave address
unction code
Register number
Value to be written
CRC
③Writing to multiple registers
Request from the customer device Master
COOLCABI Slave address
unction code
Register number
No. of registers to be written
Number of bytes
Value to be written
Value to be written
CRC
② unction code
6-bit error-detecting code. The calculation procedure of CRC is as follows.
all 6 bits are " " . This is the CRC register.
to 5 to the next 8 bits of the message. Continue this operation until all bytes
to 99 byte
3 byte
High-order
byte
Low-order
byte
High-order byte
Low-order byte
Low-order byte
High-order
byte
to 99
6
High-order
Low-order
High-order
Low-order
Low-order
High-order
to 99
6
High-order
Low-order
High-order
Low-order
n
High-order
Low-order
n byte
High-order
Low-order
・
・
・
Low-order
High-order
byte ③ Data division
COOLCABI Slave address
unction code
Number of bytes
Data
CRC
byte
COOLCABI Slave address
byte
unction code
byte
Register number
byte
byte
Written value
byte
byte
CRC
byte
COOLCABI Slave address
byte
unction code
byte
byte
Register number
byte
byte
No. of written registers
byte
byte
CRC
byte
byte
52
-37 bytes ④ Error check CRC
☞
See page 43 .
Response from COOLCABI Slave
Low-order
High-order
Response from COOLCABI Slave
High-order
Low-order
High-order
Low-order
Low-order
High-order
Response from COOLCABI Slave
High-order
Low-order
High-order
Low-order
Low-order
High-order
bytes
to 99 byte
3 byte
n byte
n byte
byte
byte
to 99 byte
6 byte
byte
byte
byte
byte
byte
byte
to 99 byte
6 byte
byte
byte
byte
byte
byte
byte