Analog.inputs.and.outputs - Siemens Simatic S7 Series Manual

Analog Inputs and Outputs
Many.PLCs.also.work.with.analog.I/O.devices..Analog.devices.
use.signals.that.are.continuously.variable.within.a.specified.
range,.such.as.0.to.0.VDC.or.4.to.20.mA.
Analog.signals.are.used.to.represent.variable.values,.such.as.
speed,.rate.of.flow,.temperature,.weight,.level,.etc..In.order.to.
process.an.input.of.this.type,.a.PLC.must.convert.the.analog.
signal.to.a.digital.value..S7-200.PLCs.convert.each.analog.
voltage.or.current.value.into.a.2-bit.digital.value.
Digital.values.from.analog.inputs.are.stored.in.addressable.
memory.for.use.by.the.user.program..Similarly,.the.user.
program.can.place.digital.values.in.addressable.memory.
locations.for.conversion.to.analog.values.for.the.designated.
analog.outputs.
The.only.S7-200.CPU.model.with.analog.I/O.points.on.board.
is.CPU.224XP ,.which.has.2.analog.inputs.and..analog.output..
However,.analog.I/O.points.can.be.added.using.expansion.
modules.for.any.CPU.other.than.CPU.22..CPU.222.allows.
for.2.expansion.modules.and.the.remaining.CPUs.allow.for.7.
expansion.modules.
Expansion.modules.are.available.with.4.or.8.analog.inputs,.
2.or.4.analog.outputs,.or.4.analog.inputs.and..analog.
output..In.addition,.expansion.modules.are..available.for.use.
with.thermocouples.or.RTD.type.sensors.which.sense.the.
temperature.at.a.specific.point.in.a.machine.or.process..
SF/DIAG
Analog Expansion Module
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