AH500 Programming Manual API 1807 Symbol: S ： Initial device to which the CRC is applied Word n ： Number of bytes Word D ： Initial device in which the operation result is stored Word Explanation: 1. Please refer to the additional remark on the instruction CRC for more information about the CRC check code. 2. The operand n should be within the range between 1 and 1000. If n is not within the range, the operation error occurs, the instruction is not executed, SM0 and SM1 are ON, and the error code in SR0 is 16#200B. 3. The 16-bit conversion mode: When SM606 is OFF, the hexadecimal data in the device specified by S is divided into the high 8-bit data and the low 8-bit data.
The CRC is applied to every byte, and the operation result is stored in the high 8-bit and the low 8-bit in the device specified by D . The number of bytes depends on n . 4. The 8-bit conversion mode: When SM606 is ON, the hexadecimal data in the device specified by S is divided into the high 8-bit data (invalid data) and the low 8-bit data. The CRC is applied to every byte, and the operation result is stored in the low 8-bit in the two registers. The number of bytes depends on n . Example: 1. The PLC is connected to the VFD-S series AC motor drive (RTU mode: SM210 is ON; 16-bit mode: SM606 is ON.).
The value 16#12, which will be written into the device at 16#2000 in the VFD-S series AC motor drive, is written into the device in the PLC first. PLC VFD-S The PLC sends 01 06 2000 0012 02 07. 6-414 Instruction code Operand Function CRC S, n, D Cyclic Redundancy Check Device X Y M S T C HC D L SM SR E PR K 16# “$” DF S n D Pulse instruction 16-bit instruction (7 steps) 32-bit instruction - AH500 -