The 4-20 mA loop is instrumentation's honest workhorse — until the cable run costs more than everything attached to it. Tank farms, remote wellpads, pipeline right-of-ways and across-plant monitoring points all reach the price where wireless pays, and Accutech's BR base-radio family is the industrial argument: 900 MHz or 2.4 GHz networks, Modbus RTU/TCP integration, and node counts up to a hundred per base station.
What the wired loop still owns
Determinism and power. A loop is powered, immune to RF planning, and as real-time as the scan rate demands — safety functions, control-critical signals and high-speed data stay wired as a matter of architecture, not sentiment. The loop also carries no radio-site survey, no frequency coordination and no battery philosophy; its complexity is the cable tray.
What the base-radio network buys
The measurement where the measurement is. The BR family's field units instrument the point locally — pressure, temperature, level — and report over the radio mesh to the base station, which hands the plant Modbus RTU or TCP into its existing control layer. A hundred points per base station turns a cable-drawing exercise into a site-survey exercise, and tank farms that would have needed trenches get instrumented in days.
The decision rule
Cable cost per point against radio cost per point — and the crossover arrives sooner than budget culture expects. Control and safety loops stay wired; monitoring populations, remote and scattered points, go wireless. Plants run both as a portfolio, and the discipline is keeping the safety study's boundaries clean between the two worlds.
How reliable is a hundred-node radio network?
Engineered honestly — mesh topologies with multiple paths, managed frequencies and real site surveys — it runs for years. Engineered casually, it drops points in the same weather that drops everything. The radio is instrumentation: survey it, commission it, and treat the link budget like a loop calculation.
What about power for the field units?
Long-life batteries are the family's answer, with solar assists where duty demands. Battery philosophy belongs in the maintenance plan — a wireless program without a battery calendar is a future outage calendar.
