AS-i field module for RTD inputs
The Siemens 3RK1207-3BQ44-0AA3 is an AS-Interface compact module K60 analog with four inputs for thermal resistors — Pt100, Ni100, or 0...600 Ohm resistive sensors. It's an analog slave on the AS-i bus, drawing up to 100 mA from the profile conductors at 30 V, with a separate 24...30 V auxiliary supply for the sensors. The 16-bit A/D resolution gives you fine granularity on the temperature or resistance reading, and the smoothing function is configurable per channel. This is a field-mount module — IP67, M12 screw-type connectors for the 4-wire sensors, and a housing that takes the washdown environment on a brewery or dairy line. Mounting plate 3RK1901-0CA00 is required but sold separately; the module clips onto standard rail or wall-mounts via that plate.
The four analog inputs are configured for 2-, 3-, or 4-conductor sensors — the 4-wire connection eliminates lead resistance error on long cable runs. The adjustable measuring range covers PT100, Ni100, or a generic 0...600 Ohm resistive input, so one module handles multiple sensor types without a hardware swap. The AS-i bus voltage is 26.5...31.6 V per spec, and the module draws its profile current from that bus. The auxiliary sensor supply (Uaux) runs at 24...30 V and can deliver up to 500 mA to the field devices — enough for four active sensors. Without Uaux, the module's own consumption drops to 46 mA max, which is useful if you're powering sensors locally. The ID code is 3, profile 7.3, I/O configuration 7 — these are the AS-i addressing parameters that the master needs to recognize the analog slave. If you're swapping a failed module on a live line, confirm the master's configuration matches these values or you'll get a fault LED.
Panel and field integration
Mounting requires the separate 3RK1901-0CA00 plate — order it alongside the module if you don't already have one. The module snaps onto standard DIN rail or wall-mounts via that plate. Dimensions are 60 mm wide, 152 mm high, 29 mm deep — compact enough for a crowded junction box or a small field enclosure. The M12 screw terminals accept standard 4-wire sensor cables. The green AS-Interface LED and green AUX PWR LED give you a quick visual on bus and sensor supply status; the red FAULT LED lights on configuration mismatch or sensor wire break.