Limits imposed by the Modbus licenses

This topic documents the limits imposed by the Modbus licenses.

RS-485 limits

<feature name="mstp"  expiration="2025-01-31"  port.limit="5"/>

port.limit defines the number of MS/TP trunks ( RS-485 ports) that can be used. This ranges from 1 to 6, varies based on the type of host controller and depends on the license purchased.

Due to electrical considerations, the EIA-485 (or RS-485) load factor of connected MS/TP devices determines how many devices a trunk can physically support. This ranges from 31 (full load) to up to 127 (quarter load) devices.

Other device or platform limits in the license’s modbus feature also apply.