OHM ELECTRIC COOL CABI OCA-H1000BC-AW2, Instruction Manual

Page: 52 / 88

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
②
unction code byte
③
Data division -37 bytes
④
Error check CRC bytes
①
Slave address
Communication address for COOLCABI Slave . The value is set by the parameter Ad
☞
See page 43 .
②
unction code
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.
③
Data division
Data to execute the function code. The structure of data division differs by function code.
④
Error check
CRC is a -byte 6-bit error-detecting code. The calculation procedure of CRC is as follows.
Load the register of all 6 bits are “ ” . This is the CRC register.
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 to 5 to the next 8 bits of the message. Continue this operation until all bytes
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
①
Reading of multiple registers
Request from the customer device Master
COOLCABI Slave address to 99 byte
unction code 3 byte
Register number
High-order
byte
Low-order byte
Number of read register
High-order byte
Low-order byte
CRC
Low-order
byte
High-order byte
②
Writing to a single register
Request from the customer device Master
COOLCABI Slave address to 99 byte
unction code 6 byte
Register number
High-order byte
Low-order byte
Value to be written
High-order
byte
Low-order
byte
CRC
Low-order byte
High-order byte
③
Writing to multiple registers
Response from COOLCABI Slave
COOLCABI Slave address to 99 byte
unction code 3 byte
Number of bytes n byte
Data n byte
CRC
Low-order byte
High-order
byte
Response from COOLCABI Slave
COOLCABI Slave address
to 99 byte
unction code 6 byte
Register number
High-order
byte
Low-order byte
Written value
High-order byte
Low-order
byte
CRC
Low-order
byte
High-order byte
Response from COOLCABI Slave
COOLCABI Slave address to 99 byte
unction code 6 byte
Register number
High-order
byte
Low-order
byte
No. of written registers
High-order byte
Low-order byte
CRC
Low-order
byte
High-order
byte
Request from the customer device Master
COOLCABI Slave address to 99 byte
unction code 6 byte
Register number
High-order
byte
Low-order
byte
No. of registers to be written
High-order byte
Low-order byte
Number of bytes n byte
Value to be written
High-order
n byte
Low-order
Value to be written
High-order
Low-order
・
・
・
CRC
Low-order byte
High-order byte