PLC Inspector

PLC Inspector is a diagnostic tool for Siemens LOGO! controllers. Read memory, watch values change live and write registers deliberately, over Modbus/TCP, straight from your phone or tablet.

MAIN FEATURES

• Read memory

VM memory, analogue inputs (AI) and analogue outputs (AQ) of your LOGO! in real time. Ranges larger than the Modbus limit are split into several requests automatically.

• Write registers

Enter values in decimal or hexadecimal and send them to the controller. The app checks what the controller echoes back and says so separately when the confirmation does not match what was sent.

• Safe writing

Write mode has to be armed deliberately and switches itself off when you leave the view. Every write is preceded by a confirmation naming the register and the value in plain words. During longer work it can be suppressed for the session, and while it is off the app says so on screen.

• Bit level view

Every register as a 16 bit value, with each bit shown separately and every fourth one marked, so nibbles can be counted without counting digits.

• Change detection

Values that changed since the previous read are highlighted. Step from one change to the next with the arrow buttons.

• Automatic refresh

Refresh at intervals from 0.5 to 10 seconds. Each read waits for the previous one to finish, so requests never pile up on the controller.

• Several controllers

Manage as many stations as you need, each with its own memory range and refresh interval.

• Made for tablets

On a tablet the station list and the memory view sit side by side, and the table places several registers next to each other instead of leaving half the screen empty.

TYPICAL USES

- Commissioning and fault finding at the cabinet

- Mobile process monitoring

- Analysing what a controller actually holds in memory

REQUIREMENTS

The Modbus server has to be enabled on the LOGO!. It is off by default and is switched on in LOGO! Soft Comfort under the network settings. The LOGO! web server on port 80 works independently of it, so a reachable web interface does not mean Modbus is running.

Only LOGO! 8 (0BA8) speaks Modbus/TCP. Earlier generations do not.

PRIVACY

The app talks to your controller directly over your own network. No cloud, no intermediate server, no account, no tracking. Your stations are included in Android's backup for your Google account, and can be exported to a file at any time. Only name, address, port and offset are stored, never a password.

PRO

Reading memory, inspecting bits and monitoring registers are free and stay free. Writing single registers is a one-time purchase, no subscription.