Delta DVP-ES2 - Manual (Page 339)

3 . I n s t r u c t i o n S e t
3 - 2 2 3
Field Name Descriptions
Address Communication address: n 8-bit binary
Function Function code: n 8-bit binary
DATA (n-1)
…….
DATA 0
Data:
n × 8-bit data
CRC CHK Low
CRC CHK High
CRC checksum:
16-bit CRC consists of 2 8-bit binary data
END Refer to the following explanation
START/END:
RTU Timeout Timer:
Baud rate(bps) RTU timeout timer (ms) Baud rate (bps) RTU timeout timer (ms)
300 40 9,600 2
600 21 19,200 1
1,200 10 38,400 1
2,400 5 57,600 1
4,800 3 115,200 1
Address:
00 H: Broadcasting to all drives (Broadcast)
01 H: toward the drive at address 01
0F H: toward the drive at address 15
10 H: toward the drive at address 16
… and so on, max. address: 254 (‘FE’)
Function code:
03 H: read contents from multiple registers
06 H: write one word into single register
10 H: write contents to multiple registers
Data characters:
The data sent by the user
CRC checksum: Starting from Address and ending at Data Content. The calculation is as follows:
Step 1: Set the 16-bit register (CRC register) = FFFFH
Step 2: Operate XOR on the first 8-bit message (Address) and the lower 8 bits of CRC
register. Store the result in the CRC register.
Step 3: Right shift CRC register for a bit and fill “0” into the highest bit.
Step 4: Check the lowest bit (bit 0) of the shifted value. If bit 0 is 0, fill in the new value
obtained at step 3 to CRC register; if bit 0 is NOT 0, operate XOR on A001H and the
shifted value and store the result in the CRC register.
Step 5: Repeat step 3 – 4 to finish all operation on all the 8 bits.