The Watlow 988A-22FD-MRRG is a 1/8 DIN microprocessor-based process controller engineered for precise temperature and multi-variable control in industrial applications. This compact vertical-mount unit delivers single-unit cascade control—a capability uncommon in 1/8 DIN form factor controllers—alongside proportional, differential, and dual-group PID control modes. It supports heater current monitoring, remote setpoint input, ratio control, and valve control via slidewire feedback with expanded auto-tuning and enhanced alarm functionality.
Technical Specifications
Control Architecture
• Microprocessor-based temperature/process controller
• 10 Hz sampling rate
• Dual universal analog inputs plus one optically isolated digital event input
• Supports thermocouple and RTD sensor inputs
• Process inputs: 0–20 mA or 4–20 mA dc (7 ohm input impedance)
Output Configuration
• Up to four total outputs (configurable)
• 4–20 mA process retransmit output
• 0–10 V dc retransmit output
• RS-232 communications output
• External signal conditioner power supplies (up to three outputs definable as 24 V dc supplies)
Control Modes
• Single-unit cascade control
• Proportional, differential, and dual-group PID
• Duplex heating/cooling control
• Ratio control with slidewire feedback valve control
• Auto-tuning capabilities with enhanced alarm functionality
Physical & Electrical
• Form factor: 1/8 DIN vertical mount
• Panel depth: 4.00 inches (102 mm)
• Power supply: 100–240 V ac, 50/60 Hz
• Front panel: NEMA 4X rated, water and corrosion resistant
• Display: Red upper/green lower readout
– Key Features
• Single-unit cascade control integrated into compact 1/8 DIN chassis
• Heater current monitoring for system performance diagnostics
• Proportional control with manual reset option
• Remote setpoint input for distributed control architectures
• RS-232 communications for system integration
• Process inputs accept 7 ohm impedance loads; external resistor (100–400 ohms typical) recommended for certain 4–20 mA transmitters to prevent inrush current damage
– Typical Applications
Temperature and process control in thermal processing, industrial ovens, heating systems, and applications requiring cascade or ratio control logic.
– Compatibility & Integration
RS-232 communications interface supports data integration. Accepts standard thermocouple and RTD inputs. Compatible with 4–20 mA and 0–20 mA process transmitters.
