Dwyer RSME-B-004 : Room Status Monitor, 0 to 1.0 in w.c., +/-0.5% RSS Accuracy, Plastic Bezel, 4.3 in Color Touchscreen, BACnet MS/TP + Modbus RTU, 24 VAC/VDC

The RSME-B-004 is a Room Status Monitor with a 4.3" color touchscreen that monitors low differential pressure across the 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). Major differences vs. the older RSM series: a full-color touchscreen instead of monochrome LCD, ability to monitor up to 3 rooms per unit with 4 parameters each, BACnet MS/TP and Modbus RTU comms standard (RSM has BACnet as an option only), USB-C clone-programming for fast multi-unit deployment, and a shallow 1.1" flush-mount depth.

Unidirectional ranges fit applications where the room runs consistently positive relative to the reference space — pharmaceutical clean rooms, protected environments for immunocompromised patients, vivariums maintained at positive containment. For rooms that can switch direction (positive for protective isolation, negative for source isolation), use the bidirectional variant (RSME-B-015) with the same accuracy spec covering both polarities.

RSS (Root Sum Squared) combines three independent accuracy components into a single specification: non-linearity (±0.49% BFSL), hysteresis (±0.05%), and non-repeatability (±0.05%). At full scale on this 0 to 1.0 in w.c. range, that works out to ±0.005 in w.c. The spec applies after a 1-hour warm-up and includes thermal effects of ±0.02% FS/°F. For cost-sensitive applications where this accuracy is overkill, see the RSME-C-004 variant with ±1.0% RSS.

Both protocols are standard on every RSME — 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 RSME 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 piezoresistive 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, calculated from external sensors), 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 clean-room corridor needs at-a-glance status of several adjacent rooms.

Order the corresponding -SS variant (RSME-B-004-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 RSME 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-RSME-BOX surface-mount box accessory — it lets the RSME mount completely on the wall surface with conduit entry from the side or back. See the recommended accessory section above.

Every RSME ships with a USB-A flash drive and a USB-C port on the unit. After you configure one RSME (setpoints, units, alarm thresholds, BACnet/Modbus address scheme, room layouts, everything), you can export the entire configuration to the flash drive in a single menu operation, then import it into the next RSME via the same port. For a facility installing 20+ RSME units across multiple isolation rooms or clean spaces, this drops per-unit configuration time from 15–30 minutes to about 2 minutes. The clone-import preserves device-specific identifiers (MAC, BACnet device instance) that need to differ between units.