Siemens Simatic S7 Series Manual page 23

Power Sources.
Mode Switch and Analog.
Adjustment.
Depending.on.the.CPU.model,.an.S7-200.CPU.is.powered.from.
either.a.24.VDC.or.a.20.to.240.VAC.power.supply..For.example,.
an.CPU.22.DC/DC/DC.model.is.powered.from.a.24.VDC.power.
supply.and.a.CPU.222.AC/DC/Relay.model.is.powered.from.a.
20.or.240.VAC.power.supply.
Each.S7-200.CPU.has.a.mode switch.with.three.positions,
RUN,.STOP,.and.TERM..When.the.mode.switch.is.in.the.
RUN.position,.the.CPU.is.in.the.RUN.mode.and.executing.the.
program,.unless.a.fault.has.occurred..When.the.mode.switch.
is.in.the.STOP.position,.the.CPU.is.in.the.STOP.mode.and.
not.executing.the.user.program..When.the.mode.switch.is.in.
the.TERM.position,.the.programming.device.can.select.the.
operating.mode.
22
DC Voltage Source
24 VDC
(Nominal Voltage)
AC Voltage Source
120 to 240 VAC
(Nominal Voltage)