Modbus polling and timeout budget: calculate the slow path
Estimate serial transaction time, include silent intervals and device response, and prevent offline devices from consuming the entire polling cycle.
RTU
Rugged controller for distributed infrastructure assets.
Remote terminal unit: a rugged controller for geographically distributed assets (pipelines, water, utilities), typically speaking DNP3, Modbus, or IEC 60870 and reporting to SCADA over radio, cellular, or serial links.
See also: PLC · SCADA · Modbus
Use the concept: Industrial automation fundamentals · PLC FAT & SAT checklist template · OT backup & restore test template
In depth
SCADA architecture: a design guide from field to control room
Design SCADA systems that scale — field layer, communications, servers, redundancy, and alarming — without painting the project into a corner.
Modbus RTU vs Modbus TCP: a practical guide
The world's most common industrial protocol in its two dominant forms — framing, addressing, gateways, and the mistakes that break integrations.