7 Application Instructions API 50-99 In RTU mode (M1143 = On) Address: 00H: Broadcasting to all drivers 01H: To the driver at address 01 0FH: To the driver at address 15 10H: To the driver at address 16…. And so on, maximum to the driver at address 254 (FE H) Function code: 02H: Reading several bit devices 03H: Reading several word devices 04H: Reading several word devices (read-only devices) 05H: Writing a state in a single bit device 06H: Writing data in a single word device 0FH: Writing states in bit devices 10H: Writing data in word devices 17H: Reading word devices and writing data in word devices Data characters: The data sent by the user. CRC checksum:
Starting from Address and ending at Data Content. Step 1: Make the 16-bit register (CRC register) = FFFFH Step 2: Exclusive OR the first 8-bit message and the low 16-bit CRC register. Store the result in the CRC register. Step 3: Right shift CRC register for a bit and fill “0” into the high bit. Step 4: Check the value shifted to the right. If it is 0, fill in the new value obtained in step 3 and store the value in CRC register; otherwise, Exclusive OR A001H and CRC register and store the result in the CRC register. Step 5: Repeat step 3 – 4 and finish operations of all the 8 bits. Step 6:
Repeat step 2 – 5 for obtaining the next 8-bit message until the operation of all the messages are completed. The final value obtained in the CRC register is the CRC checksum. The CRC checksum has to be placed interchangeably in the checksum of the message. START and END: For ES/EX/SS V5.8 (and below) and SA/SX V1.1 (and below) series MPU, keep no input signal be ≥ 10ms. DVP-PLC APPLICATION MANUAL 7-115 Name Data (hexadecimal system) START See the following explanation Address Communication address: In 8-bit binary Function Function code: In 8-bit binary DATA (n-1) Data: n × 8-bit data ……. DATA 0 CRC CHK Low CRC checksum:
16-bit CRC consists of 2 8-bit binary CRC CHK High END See the following explanation