Foxboro RH924JH Quad-Alarm Dual-Input Panel Indicator

Technical Specifications:

• Input Channels: 2 universal inputs (independent)
• Input Types: Type J, K, T, E, S, R, B TC; Pt100, Pt1000 RTD; 4–20 mA; 0–10 V; 1–5 V
• Display: Dual-line 6-digit red LED, 14 mm digits, 100,000 count
• Alarm Outputs: 4 SPDT relays (2 Hi + 2 Lo per channel), 250 V AC / 30 V DC, 3 A each
• Communication: RS-485 Modbus RTU, 9600–38400 baud
• Retransmission: Isolated 4–20 mA per channel
• Power Supply: 85–265 V AC / 90–300 V DC / 24 V DC
• Operating Temperature: -10°C to +55°C (+14°F to +131°F)
• Protection Rating: IP65 front panel
• Dimensions: 96 mm x 96 mm x 90 mm (W x H x D)
• Cutout Size: 92 mm x 92 mm
• Weight: Approximately 430 grams

Functional Features:

• 4 Programmable Alarms: 2 High and 2 Low setpoints per channel — supports pre-alarm, alarm, and shutdown hierarchy
• Independent Hysteresis: Each alarm has independently adjustable hysteresis (0.1% to 20% of span)
• Alarm Latching: Relays latch in alarm state until manually reset via keypad or remote command
• Dual Display: Simultaneous real-time display of both process variables
• Peak/Valley Hold: Per-channel peak and valley capture

Material Composition:

• Front Bezel: Flame-retardant ABS, matte black
• Housing: Polycarbonate (Lexan), IP65 gasket seal
• Display: High-brightness red LED, optical-grade polycarbonate
• Terminals: Phosphor bronze, nickel-plated

Structural Characteristics:

• Form Factor: 96 x 96 mm panel-mount (1/4 DIN)
• Keypad: 8-button membrane with dedicated alarm configuration menu
• Communication Port: RJ-11 jack (rear panel)
• Alarm Terminals: 8 screw terminals (AL1-H, AL1-L, AL2-H, AL2-L, AL3-H, AL3-L, AL4-H, AL4-L)

Working Principle:
Each of the two input channels is processed by an independent 24-bit ADC. The microcontroller continuously compares each process value against 4 user-programmable setpoints (2 Hi, 2 Lo) with independent hysteresis. When a setpoint is crossed, the corresponding SPDT relay changes state and latches. The RS-485 Modbus interface allows remote reading of all process values and alarm statuses. The dual LED displays show real-time values for both channels simultaneously.

Advantages / Highlights:

• 4 alarm relays per unit eliminate need for external alarm annunciator modules
• Independent hysteresis per alarm prevents relay chatter on boundary conditions
• Latching relays ensure alarm conditions are not missed during brief excursions
• Dual-channel monitoring with full alarm coverage on both channels
• IP65 rating for harsh industrial environments

Applicable Industries:

• Oil and Gas (safety-critical monitoring)
• Chemical Processing (hazardous area monitoring)
• Power Generation (turbine/boiler protection)
• Mining (safety interlocks)
• Water Treatment (pump protection)

Installation Requirements:

• Cut 92 mm x 92 mm panel opening
• Mount with IP65 gasket and snap-in clips
• Wire field inputs to Ch1 and Ch2 terminal blocks
• Connect alarm relay outputs to AL1 through AL4 terminals
• RS-485: A, B, GND with 120 Ω termination at bus ends
• Power: 85–265 V AC or 24 V DC to L/N or +/- terminals

Usage Precautions:

• Do not exceed 3 A per relay contact — use external contactor for motor-driven loads
• Set hysteresis appropriately — too low causes relay chatter; too high reduces alarm sensitivity
• Verify all 4 alarm setpoints before placing in service
• Test all relays using the keypad test function during commissioning
• Do not apply voltage signals to mA input terminals