Connecting the Bridge to PLCs (Siemens, Allen-Bradley)

Pulling data without touching the program

The iGromi Bridge reads production variables (tags) straight from PLC memory without stopping the machine or modifying the original ladder code.

Option A: Ethernet (Profinet / EtherNet/IP)

If your PLC has a spare Ethernet port (e.g. Siemens S7-1200/1500 or Allen-Bradley CompactLogix):

1. Connect the iGromi Bridge to the same industrial switch as the PLC.
2. Give the Bridge a static IP on the same network segment as the PLC (e.g. if the PLC is on 192.168.0.10, use 192.168.0.50).
3. In the iGromi portal, add the data source and enter the memory addresses: DB1,X0.0 (for machine state) or DB2,D4 (for a piece counter).

Option B: Serial (Modbus RTU / RS485)

For legacy PLCs or temperature controllers:

1. Use shielded twisted-pair cable (Belden 3105A or equivalent).
2. Wire A(+) and B(-) from the PLC's RS485 port to the matching terminals on the iGromi Bridge.
3. Ground the cable shield at one end only, to avoid ground loops.
4. In the iGromi portal, select Modbus RTU. Match the exact baud rate, parity and stop bits configured on the master PLC.

The Bridge starts polling the variables at 10Hz and packages them into MQTT Sparkplug B messages.