PLS (Pulse): rising differential output directive.
PLF: falling edge of differential output directive.
PLS and PLF command can only be used for the output relays and auxiliary relays (does not include special auxiliary relays). M0 in the figure only in the X0 normally open from open to close (X0 rising edge) when a scan cycle for ON,M1 only on X0 normally open contact connected become disconnected (X0 the falling edge) _ when a scan cycle is ON.
When the PLC from RUN to STOP, and then from STOP to RUN when its input signal still is ON,PLS M0 instruction will output a pulse. However, if you use the battery backup (latches) the auxiliary relays instead of M0, PLS order in this case no output pulses.