LOGO! or Relays? Let the Wiring Decide.
Two relays and a timer are still the cheapest way to switch a light. Once staircase timing, twilight switching, motion detection and holiday logic start interacting, a LOGO! module replaces the wiring with a program you can change in minutes.
Where the Threshold Sits
Count the relays
Two or three independent timers or contactors still cost less than a logic module and are simpler to fault-find.
Watch for interaction
When staircase timing has to yield to motion detection, or twilight overrides a manual switch, wiring turns into a rat's nest of auxiliary contacts.
Compare the cost of change
A relay panel needs new wiring for every new rule; a LOGO! program needs a laptop and five minutes in LOGO! Soft Comfort.
Check the I/O budget
Confirm the base module's digital inputs and outputs cover the task, or plan an expansion module before committing to LOGO!.
What LOGO! Actually Gives You
Program instead of rewire
Function blocks in LOGO! Soft Comfort replace hours of contactor wiring with a diagram you edit on screen, with built-in simulation.
Built-in simulation
Test the logic in LOGO! Soft Comfort before a single wire is connected in the panel.
Analog and digital I/O
The base unit handles digital inputs and outputs, with support for analog signals and expansion modules when the task grows.
Ethernet and Modbus TCP
The LOGO! 8 generation adds network connectivity and a built-in web server for remote monitoring.
One module, many tasks
Lighting by time or sensor, pumps, irrigation, ventilation, gates and heating logic all run on the same platform.
Panel space saved
One DIN-rail module replaces a row of timers, contactors and auxiliary relays.
Where LOGO! Stops Making Sense
For a handful of switching points, relays remain the right call; for a house full of automation points, KNX is the better platform.
- Existing DIN-rail space measured
- Number of interacting timers/relays counted
- Retrofit vs. new panel decided
- Ethernet or Modbus TCP need identified
- Electrician's programming time budgeted
Frequently asked questions
Is LOGO! worth it for just one staircase light?
No — a single timer relay is cheaper and faster to fix. LOGO! pays off once that timer starts interacting with motion sensors, twilight switches or manual overrides.
Can LOGO! replace an existing panel without rewiring everything?
Often yes on the control side: existing switches, sensors and contactors reconnect to the module's inputs and outputs, and the logic that used to sit in wiring moves into the program.
What do electricians need to learn to use LOGO!?
The core shift is from wiring logic to programming it: function blocks in LOGO! Soft Comfort, basic simulation, and reading a function diagram instead of a wiring diagram.
Does LOGO! support network control?
The LOGO! 8 generation includes Ethernet and Modbus TCP with a built-in web server, so remote monitoring and integration with other systems is possible.
When should I choose KNX instead of LOGO!?
LOGO! suits a defined set of tasks such as lighting, pumps or gates. For a full house with many automation points across multiple rooms, KNX is the more appropriate platform.
Not Sure Which Side of the Threshold You're On?
Send us your relay count and we'll tell you honestly whether LOGO! is worth the switch.