Delta VFD4A2ME43ANNAA User Manual

Chapter 12 Description of Parameter SettingsME300
12.1-09-7
RTU mode:
Command Message
Response Message
ADR 01H ADR 01H
CMD 10H CMD 1 10H
Target register
05H
Target register
05H
00H 00H
Number of register
(count by word)
00H
Number of register
(count by word)
00H
02H 02H
Quantity of data (bytes) 04 CRC Check Low 41H
The first data content
13H CRC Check High 04H
88H
The second data content
0FH
A0H
CRC Check Low ‘9’
CRC Check High ‘A’
Checksum
ASCII mode:
LRC (Longitudinal Redundancy Check) is calculated by summing up the values of the bytes from
ADR1 to last data character then calculating the hexadecimal representation of the
2’s-complement negation of the sum.
Example:
01H + 03H + 21H + 02H + 00H + 02H = 29H, the 2’s-complement negation of 29H is D7H.
RTU mode:
CRC (Cyclical Redundancy Check) is calculated by the following steps:
Step 1: Load a 16-bit register (called CRC register) with FFFFH.
Step 2: Exclusive OR the first 8-bit byte of the command message with the low order byte of the
16-bit CRC register, putting the result in the CRC register.
Step 3: Examine the LSB of CRC register.
Step 4: If the LSB of CRC register is 0, shift the CRC register one bit to the right, fill MSB with zero,
then repeat step 3. If the LSB of CRC register is 1, shift the CRC register one bit to the
right, fill MSB with zero, Exclusive OR the CRC register with the polynomial value A001H,
then repeat step 3.
Step 5: Repeat step 3 and 4 until you perform eight shifts. This processes a complete 8-bit byte.
Step 6: Repeat step 2 through 5 for the next 8-bit byte of the command message. Continue doing
this until all bytes are processed. The final contents of the CRC register are the CRC
value. When transmitting the CRC value in the message, the upper and lower bytes of the
CRC value must be swapped, that is, the lower order byte is transmitted first.
The following is an example of CRC generation using C language. The function takes two
arguments:
Unsigned char* data  a pointer to the message buffer
Unsigned char length  the quantity of bytes in the message buffer
The function returns the CRC value as a type of unsigned integer.

Delta VFD4A2ME43ANNAA Specifications

General

Brand	Delta
Model	VFD4A2ME43ANNAA
Category	DC Drives
Language	English