7 Application Instructions API 50-99 API 60 Operands: S : Start device in the designated operation mode D 1 : The smallest No. of designated step in auto mode D 2 : The biggest No. of designated step in auto mode Explanations: 2. Range of D 1 and D 2 : for SA/SX/SC/EH/EH2/SV/EH3 /SV2 S20 ~ S899; for ES/EX/SS S20 ~ S127; D 2 > D 1 . 1. S will occupy 8 consecutive points. 3. See the specifications of each model for their range of use. 4. ES/SA series MPU does not support E, F index register modification. 5. IST instruction can only be used once in the program. 6. Flags: M1040 ~ M1047. See remarks for more details. 7.
IST instruction is a handy instruction specifically for the initial status of step ladder control procedure to accommodate special auxiliary relay. Program Example 1: 1. Use of IST instruction M1000 S X10: Individual operation X11: Zero return X12: Step operation X13: One cycle operation X14: Continuous operation X15: Zero return enabled switch X16: Start switch X17: Stop switch 2. When IST instruction is being executed, the following special auxiliary relays will switch automatically. M1040: Operation forbidden M1041: Operation starts M1042: Pulse output enabled M1047: STL monitor enabled S0: Initiates manual operation S1: Initiates zero return S2: Initiates auto operation 3.
S10 ~ S19 are for zero return and cannot be used as general steps. When S0 ~ S9 are in use, S0 ~ S2 represent manual operation mode, zero return mode and auto operation mode. Therefore, in the program, you have to write the circuit of the three steps in advance. 4. When switched to S1 (zero return) mode, any On in S10 ~ S19 will result in no zero return. DVP-PLC APPLICATION MANUAL 7-43 Mnemonic Operands Function IST Initial State Type OP Bit Devices Word Devices Program Steps X Y M S K H KnX KnY KnM KnS T C D E F IST: 7 steps S * * * D 1 * D 2 * PULSE 16-bit 32-bit SA SX SC EH SV EH3 SV2 EH3 ES EX SS SA SX SC EH SV EH3 SV2 ES EX SS ES EX SS SA SX SC EH SV SV2 IST X10 S20 S60