The IC695ALG412 is the high-speed thermocouple input module for Emerson's PACSystems RX3i platform — 12 isolated differential channels, each configurable for thermocouple types J, K, T, E, R, S, B, N, or C, with integral cold-junction compensation and open-circuit detection per channel. The sigma-delta ADC converts the low-level thermocouple signal (±150 mV or ±50 mV range, depending on configuration) to a 16-bit digital value with ±0.1% accuracy at 25 °C ambient — sufficient to resolve a Type K thermocouple to better than 0.5 °C across its -200 °C to +1372 °C range. The 12 channels share a single RX3i backplane slot, making this the highest-density temperature input module in the RX3i analog I/O portfolio: a single 10-slot rack can accommodate up to 120 thermocouple channels, enough for a multi-zone plastics extruder with barrel heaters, die heaters, melt temperature probes, and cooling water thermocouples on every zone.

Millivolt flexibility: beyond thermocouples

The ±50 mV and ±150 mV input ranges accept any low-level voltage signal — not just thermocouples. A strain gauge bridge connected in a 4-wire configuration (excitation from an external supply, differential sense pair to the IC695ALG412) produces a millivolt signal proportional to force, weight, or pressure, and the module's 16-bit resolution turns that millivolt signal into engineering units in the RX3i CPU. The open-circuit detection, normally used to flag a broken thermocouple, also detects a disconnected strain gauge or a severed bridge wire. This dual-use capability makes the IC695ALG412 a universal low-level analog front-end for the RX3i — thermocouples and strain gauges sharing the same module type, differentiated only by configuration in Proficy Machine Edition. The 12 channels, each isolated from each other and from the backplane, eliminate the ground-loop errors that plague multi-channel thermocouple installations where the sensors are welded to machine frames, pipes, and vessels at different ground potentials.