Sullivan-Palatek SP series PLC controller
Sullivan-Palatek panels are among the most Modbus-friendly OEM controllers — the full register map ships in the manual, which makes them easy to integrate into plant SCADA without a gateway.
Manufacturer
Sullivan-Palatek
Display
Monochrome text LCD (4-line) with tactile keypad; later builds use a small color HMI.
Years produced
~2008 – present on D-series industrial screws.
Power supply
24 VDC from the panel supply with fuse-protected I/O rails.
Ambient range
0 – 50 °C.
Protection rating
NEMA 12 typical in OEM panel.
Relay outputs
Starter command, load/unload solenoid, blowdown, fan motor, alarm beacon.
Used on
- Sullivan-Palatek D25 – D400 industrial rotary screws
- Some portable electric models
Features
- Modulation / load-unload / auto-dual control selectable in menu
- Adjustable service intervals with countdown hours
- Event history buffer (last ~20 events)
- Remote monitoring-ready via Modbus register map in the manual
Interfaces
- Modbus RTU slave standard
- Dry contacts remote start/stop
- Optional ethernet module on HMI builds
Sensor inputs
- Discharge temperature probe (Type J thermocouple on early builds, RTD on later)
- Discharge pressure transducer
- Sump pressure transducer
- Differential pressure switches for filters
Fault code lookup
First checks
- Oil and cooler
- Thermal valve
- Probe type matches controller configuration (J-thermocouple vs RTD)
First checks
- Inlet valve operation
- Minimum pressure valve
- Oil level / foaming
First checks
- Transducer calibration
- Unloader not seating
- Check valve leakage
First checks
- Amp draw vs FLA
- Voltage balance
- Bearing condition
First checks
- Terminal torque on the input card
- Sensor wiring chafe points at the cabinet pass-through
First checks
- Change indicated filter
- Verify differential switch tubing not kinked
Fault list is non-exhaustive and firmware-dependent. Always confirm against the controller’s on-screen help or OEM manual.
Sensor pin resistance & signal values
Pin-level resistance and signal values for the sensor types this controller uses. Works offline. De-energise the panel and lift one lead before ohming any element.
Wiring notes
- Thermocouple vs RTD selection is a controller parameter AND a hardware input — mismatch causes wildly wrong readings; verify both
- Modbus terminals are labeled A/B/GND on the lower I/O rail
- The alarm beacon output is fused at 2 A — do not power horns over that without an interposing relay
Known issues & field notes
- Early J-thermocouple builds drift in high vibration — upgrade kit converts to RTD input
- Keypad overlays cloud in wash-down environments; replacement overlays are inexpensive
Two-level access: operator and service. Service code supplied with the unit documentation packet.
Manuals & literature
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