8 Application Instructions API 100-149 API 108 Operands: S : Start operation device for RTU mode checksum n : Number of calculated bits D : Start device for storing the operation result CRC checksum: See remarks. Explanations: 2. Flags: M1161 (switching between 8/16-bit modes) 1. Range of n : K1 ~ K256 3. If n does not fall within its range, an operation error will occur, the instruction will not be executed, M1067, M1068 = On and D1067 will record the error code H’0E1A. 4. In 16-bit conversion mode: When M1161 = Off, S divides its hex data area into higher 8 bits and lower 8 bits and performs CRC checksum operation on each bit.
The data will be sent to the higher 8 bits and lower 8 bits in D . n = the number of calculated bits. 5. In 8-bit conversion mode: When M1161 = On, S divides its hex data area into higher 8 bits (invalid data) and lower 8 bits and performs CRC checksum operation on each bit. The data will be sent to the lower 8 bits in D and occupy 2 registers. n = the number of calculated bits. (All higher 8 bits in D are “0”.) Program Example: When PLC communicates with VFD-S series AC motor drives (In RTU mode, M1143 = On), (In 16-bit mode, M1161 = On), the sent data write in advance H12 into H2000 of VFD-S.
DVP-PLC Application Manual 8-18 Mnemonic Operands Function CRC P Checksum CRC Mode Type OP Bit Devices Word Devices Program Steps X Y M S K H KnX KnY KnM KnS T C D E F CRC, CRCP: 7 steps S * n * * * D * PULSE 16-bit 32-bit EH3 SV2 EH3 ES EX SS SA SX SC EH SV EH3 SV2 ES EX SS SA SX SC EH SV ES EX SS SA SX SC EH SV SV2 M1002 Set up communic MOV H87 D1120 to 9600, 8, E, 1 SET M1120 Retain communication pro Set up communic MOV K100 D1129 time-out:
100ms SET M1143 RTU Mode SET M1161 8-bit Mode transmission request Write transmitting data in advance pulse SET M1122 Set up transmission request X10 RS D100 K8 D120 K8 RS D100 K8 D120 K8 MOV H87 D1120 SET M1120 MOV K100 D1129 SET M1143 SET M1161 SET M1122