LineKeeper

New: Siemens S7 and Modbus TCP support. Don't know the tag? Press the machine's real button — the app finds it. Scan the network and connect in seconds.

LineKeeper turns your iPhone into a pocket HMI for the controllers on your plant floor — Allen-Bradley Logix, Siemens S7, and anything that speaks Modbus TCP.

Scan the network and the app finds every PLC around and tells you which ones are ready to talk. On Allen-Bradley it reads the controller's own tag list over EtherNet/IP — live values in seconds, nothing to configure: no PLC program changes, no gateway, no OPC server, no cloud account. Values go straight from the controller to your phone.

WHAT YOU CAN DO • Zero-config tag browser on Logix — every tag of every PLC, live, with search, including program-scoped tags. • Find by action — don't know the address? Press the machine's real button, or nudge a setpoint on its own screen, in the rhythm the app dictates — and the app finds the tag that followed. Works on Modbus and S7 too, where there are no tag names at all. • Network scan — one sweep fingerprints EtherNet/IP, Modbus TCP, S7 and more. A PLC with closed access shows as "found, access closed" with the exact steps to open it, down to the TIA Portal clicks. • One dashboard per machine, on multiple pages — number, gauge, LED and trend tiles on swipeable named pages ("Filler", "Capper", "Conveyors"), even when one machine runs several PLCs. • Operator panel — large start/stop buttons, hold-to-run jog, latches, setpoints and status lamps, full-screen kiosk mode with the screen kept awake. • Alarms and status codes — alarm words mapped to operator texts, a red banner over every screen while an alarm is active, and a session journal of appeared/cleared. • Guarded writes — every write is confirmed and validated against the tag type and limits; hold-to-run releases the moment the app loses focus. • Machine profiles — PLCs, register maps, pages, panel and alarm texts saved as one profile and shared as a file: enter the register map once, the next shift sees names. • Built-in demo line — two virtual PLCs with a working panel so you can learn the whole app with no hardware.

WHO IT'S FOR Controls engineers, integrators and maintenance techs who need a quick window into a controller during commissioning, troubleshooting, or a line-down call — without carrying a laptop.

HOW IT CONNECTS Your phone must be on the same network as the controller (plant Wi-Fi that routes to the PLC, or a USB-C Ethernet adapter). There is no cloud relay: if you can ping the PLC, the app can connect.

SUPPORTED CONTROLLERS • Allen-Bradley CompactLogix and ControlLogix (the tag-based Logix 5000 family) over EtherNet/IP. • Siemens S7-300 and S7-400 out of the box; S7-1200 and S7-1500 with PUT/GET enabled and non-optimized DBs — the app shows the exact TIA Portal steps. Absolute addressing: DB, M, I/Q. • Modbus TCP devices — Schneider, VFDs, energy meters, WAGO, Delta and other Modbus slaves, with per-connection unit ID and word-order settings. Micro800, SLC-500, PLC-5, LOGO! and S7-200 use different protocols and are not supported yet.

SAFETY Writing a value can move real machinery. You remain responsible for safe operation and must follow all site safety procedures. Never rely on the app for an emergency stop or any safety function. See the full terms at linekeeper.net/terms.html.