8 Application Instructions API 100-149 API 107 Operands: S : Start operation device for ASCII mode checksum n : Number of calculated bits D : Start device for storing the operation result LRC checksum: See remarks. Explanations: 2. See the specifications of each model for their range of use. 1. Range of n : K1 ~ K256 3. Flag: M1161 (switching between 8/16 bit modes) 4. n has to be even. 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. 5. In 16-bit conversion mode:
When M1161 = Off, S divides its hex data area into higher 8 bits and lower 8 bits and performs LRC 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. 6. 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 LRC 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 bits in D are “0”.) Program Example:
When PLC communicates with VFD-S series AC motor drives (In ASCII mode, M1143 = Off), (In 8-bit mode, M1161 = On), the sent data write in advance the 6 data read starting from H2101 of VFD-S. MOV D1120 H86 M1002 Set up communication protocol to 9600, 7, E, 1 SET M1120 Retain communication protocol sending request pulse MOV D1129 K100 Set up communication time-out: 100ms Write in sent data in advance pulse SET M1122 Set up transmission request X10 RS K35 receiving completed M1123 Process of receiving data RST M1123 Sending/receiving of data is completed. The flag is reset.
DVP-PLC Application Manual 8-16 Mnemonic Operands Function LRC P Checksum LRC Mode Type OP Bit Devices Word Devices Program Steps X Y M S K H KnX KnY KnM KnS T C D E F LRC, LRCP: 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 D100 K17 D120