The Omron K3HB-RNB-C2 is a Rotary Pulse Indicator from the K3HB-R series, a digital panel indicator that reads pulse inputs from rotary encoders or similar NPN/voltage pulse sources and displays the count or rate on its front panel. The C2 output code means it comes with four SPST-NO relay contacts (HH, H, LL, L), each independently set for high/low alarm thresholds. Power supply flexibility is built in: it accepts 100 to 240 VAC, 24 VAC/VDC, or 24 VDC via a DeviceNet power supply connection, so it fits into both line-voltage and 24 VDC control circuits without an external converter.
The K3HB-RNB-C2 is a fast mover for panel builders and MRO stockrooms that standardize on the K3HB-R series for rate and count display. Keep one on the shelf if your line uses NPN pulse outputs and needs four relay setpoints — the min/max level is one unit per panel or two for critical spares.
The NB input code means it is wired for NPN open-collector or voltage pulse inputs — common for incremental rotary encoders and flow meters. If your sensor is PNP, you would need the PB input variant; this one expects the signal to sink to common. The four relay outputs (HH/H/LL/L) are each SPST-NO, rated for general-purpose switching of alarms, counters, or small pilot loads. They are not intended for direct motor or solenoid switching without an interposing contactor — treat them as signal-level outputs to a PLC or relay bank. Ambient operating temperature spans −10 to 55°C with 25% to 85% humidity, and storage goes to −25 to 65°C.