Delta Electronics Programmable Logic Controller DVP-PLC - Manual (Page 130)

2 Functions of Devices in DVP-PLC
DVP-PLC Application Manual
2-102
Device No. Function
M1170 Start flag
M1171 Action flag
D1170 STEP No. of the currently executed instruction
2. The function:
a) Execution timing: The flag is valid only when PLC is in RUN status.
b) Action steps:
i) When M1170 is enabled, PLC enters the single step execution mode. PLC stays at a specific instruction,
stores the location of STEP in D1170 and executes the instsruction once.
ii) When M1171 is forced “On”, PLC executes the next instruction and stops. At the same time, PLC
auto-force “O ff” M1171 and stops at the next instruction. D1170 stores the present STEP value.
iii) When Y output is in single step execution mode, Y outputs immediately without having to wait until END
instruction is being executed.
3. Note:
a) Instruction that will be affected by scan time will be executed incorrectly due to the single step execution. For
example, when HKY instruction is executed, it takes 8 scan times to obtain a valid input value from a key.
Therefore, the single step execution will result in incorrect actions.
b) High-speed pulse input/output and high-speed counter comparison instructions are executed by hardware;
therefore, they will not be affected by the single step execution.
Function Group 2-phase Pulse Output
Number M1172 ~ M1174, D1172 ~ D1177
Contents:
1. Special D and special M for two-phase pulse output for SA/SX/SC:
Device No. Function
M1172 Switch for two-phase pulse output (On = enabled)
M1173 On = Continuous output switch
M1174 “Number of pulses reached” flag
D1172 Output frequency (12Hz ~ 20KHz)
D1173 Output mode (K1 and K2)
D1174 The lower 16 bits of the 32 bits for the target number of pulses
D1175 The higher 16 bits of the 32 bits for the target number of pulses
D1176 The lower 16 bits of the 32 bits for the present number of pulses
D1177 The higher 16 bits of the 32 bits for the present number of pulses
2. The function:
Output frequency = 1/1 pulse cycle period (i.e. 1/T; as the figure below)