What is the maximum number of Modbus slave devices that an industrial AI edge gateway can connect to simultaneously?

Industrial AI edge gateway RS485 ports typically support 32-64 Modbus slave devices. When the number of connected devices is large, the bus parasitic capacitance increases, signal edges become slower, and common-mode interference is more easily coupled. Countermeasures include:

1. Connecting a 120Ω terminating resistor in parallel to ground on the A/B lines of the gateway side, and a common-mode inductor CML3225A-510T in series.

2. Using an isolated DC-DC converter for each RS485 power supply, and adding a TVS ESDSM712.

3. Connecting one end of the bus cable shielding to ground and fitted with a ferrite core CMZ7060A-701T with an impedance of 700Ω.

In actual testing at 100MHz with 48 slave devices connected, the communication rate was 19.2kbps, and the packet loss rate was <0.01%, meeting the AI data acquisition requirements.