Dwyer RSMC-A-015 : StabiliSENSE Critical Room Status Monitor, -1.0 to 1.0 in w.c., +/-0.25% RSS Accuracy, Plastic Bezel, 4.3 in Color Touchscreen, BACnet MS/TP + Modbus RTU, 24 VAC/VDC

The RSMC-A-015 is a critical-tier wall-mounted Room Status Monitor with a 4.3" color touchscreen that monitors low differential pressure across the -1.0 to 1.0 in w.c. range and can also display up to 3 additional parameters per room (relative humidity, temperature, air changes per hour, door status). StabiliSENSE™ is Dwyer's branding for the capacitance cell pressure sensor used in the RSMC — it's the long-term-stable, low-drift sensing technology that justifies the “critical” positioning vs. lower-tier monitors. Up to 3 rooms per unit, BACnet MS/TP and Modbus RTU comms standard, factory calibration certificate included.

Two main differences: sensor technology and accuracy tiers. The RSMC uses a capacitance cell pressure sensor — inherently more long-term stable than the piezoresistive sensors in the RSME, with reduced drift over the operating life. Accuracy options on the RSMC are ±0.25% RSS (-A) and ±0.5% RSS (-B); the RSME tops out at ±0.5% (-B) and goes down to ±1.0% (-C). Pick the RSMC for FDA / USP / ISO-regulated critical environments where long-term stability and a factory calibration certificate are required; the RSME is appropriate for lower-criticality applications where the cost difference matters more than the long-term stability margin.

Bidirectional ranges (-X to +X around zero) are required when the monitored room can swing either side of neutral — for instance, a hospital room that runs positive for protective isolation (immunocompromised patients) and negative for source isolation (infectious patients), or a semiconductor cleanroom that switches between containment directions. The RSMC-A-015's -1.0 to 1.0 in w.c. range with ±0.005 in w.c. resolution at full scale handles both polarities with a single SKU. If your room only ever runs positive, the corresponding unidirectional variant (RSMC-A-004) is functionally equivalent at half the working range with the same accuracy spec.

RSS (Root Sum Squared) combines three independent accuracy components into a single specification: non-linearity (±0.24% BFSL), hysteresis (±0.05%), and non-repeatability (±0.05%). At full scale on this -1.0 to 1.0 in w.c. range, that works out to ±0.005 in w.c. For applications where this accuracy is more than required, see the RSMC-B-015 variant with ±0.5% RSS (same hardware, looser calibration tolerance, lower cost). Both tiers use the same StabiliSENSE™ capacitance cell sensor.

Both protocols are standard on every RSMC — no order option, no SKU difference. Configure which protocol is active via the touchscreen menu. BACnet MS/TP runs on the isolated RS-485 port for direct BAS integration; Modbus RTU runs on the same RS-485 port for industrial control or SCADA integration. The unit cannot run both simultaneously on the same RS-485 bus, but switching between them is a menu setting (no firmware change or factory reset needed).

The RSMC can be configured to display up to 3 separate monitored rooms from a single touchscreen, with up to 4 parameters per room: differential pressure (from the internal capacitance cell sensor for the primary room, or from external transmitters wired into the analog inputs for additional rooms), relative humidity, temperature, air changes per hour (ACH), and door status (from the digital input). The configurable GUI lets you choose layout and which parameters are visible. Useful when a single nurses' station or cleanroom corridor needs at-a-glance status of several adjacent rooms.

Order the corresponding -SS variant (RSMC-A-015-SS) if your installation environment requires clinical wash-down cleaning (most hospital infection-control protocols), if the install location is exposed to aggressive disinfectants (pharmaceutical clean spaces, vivariums), or if the architectural spec calls for stainless steel finishes throughout. The standard plastic bezel is fine for office environments, dental and school nurse offices, and other non-wash-down applications.

Standard installation is flush in-wall at a 1.1" depth into a double-gang opening — the included junction box mounts behind the wall and the RSMC snaps onto the junction box. For installations where flush mounting isn't possible (concrete walls, retrofit jobs without behind-wall access, or temporary installations), order the A-RSMC-BOX surface-mount box accessory — it lets the RSMC mount completely on the wall surface with conduit entry from the side or back. See the recommended accessory section above.