Analog Signals with Siemens LOGO!
Beyond digital on/off: LOGO! analog expansion modules read sensors and drive 0-10V actuators, with scaling handled in the program — enough for temperature-led pump control, fan or damper output, and light-level switching.
How analog I/O works in a LOGO! system
Reading the signal
An analog expansion module reads a sensor — temperature, light level, or a 0-10V signal — as a raw input value.
Scaling in the program
The raw value is converted to engineering units using scaling function blocks in the FBD program.
Driving the output
The program computes a 0-10V output signal for a fan, damper, or valve actuator.
Commissioning and testing
The scaled response is checked against real sensor readings and simulated in LOGO! Soft Comfort before going live.
What analog I/O adds to a LOGO! system
signal types, one module
Analog inputs and outputs share the same expansion module family as digital I/O, so a single LOGO! base unit with an analog expansion can mix sensor reading and actuator control in one program.
Analog expansion modules
Add analog inputs and outputs to a LOGO! base module without moving to a separate PLC platform.
Value scaling in FBD
Raw sensor readings are converted to real-world values — degrees, percent, lux — using scaling blocks in the program, not extra hardware.
Temperature-led pump control
A temperature input drives pump start/stop or speed logic, replacing a standalone thermostat with programmable logic.
0-10V fan and damper output
An analog output signal proportionally controls fan speed or damper position instead of simple on/off switching.
Light-level input
An analog light sensor feeds the program directly, enabling threshold or dimming logic without extra relays.
What our engineers bring to an analog LOGO! project
From signal selection to a tested, documented system.
- Base module and analog expansion selection for your I/O count
- FBD program with scaling blocks, tested in simulation
- Cabling and shielding guidance for low-level analog signals
- Panel assembly on DIN rail with clearly labeled terminals
- Documented program copy and wiring diagram at handover
Frequently asked questions
What can LOGO! analog inputs and outputs actually do?
Analog expansion modules read continuous signals such as temperature or a 0-10V sensor output, and drive proportional 0-10V outputs to actuators like fans or valves — the base module handles digital I/O, expansions add the analog range.
Where does the value scaling happen?
Inside the LOGO! program itself, using function blocks in LOGO! Soft Comfort (FBD) — raw analog readings are converted to engineering units such as degrees or percent before your control logic uses them.
What's a typical analog use case?
Temperature-led pump control, 0-10V fan or damper speed output, and light-level input for lighting or shading logic are the most common in small commercial and technical-room installations.
What cabling practice matters for analog signals?
Low-level analog signals are sensitive to electrical noise, so shielded cable, separation from power wiring, and a single-point earth for the shield are standard practice to keep readings stable.
When do we need a bigger PLC instead of LOGO!?
When accuracy requirements, analog channel count, or control complexity exceed what LOGO!'s expansion modules and FBD logic can comfortably handle, a full PLC platform gives more I/O density and precision.
Planning analog I/O for a LOGO! system?
Tell us your sensors and actuators — our engineers will confirm the right modules and scaling approach.