In Part 1 of “Tech Jargons Explained: A Simplified Guide to Industrial Controls and Instrumentation from MurCal,” we covered the core terms behind Swichgages®, gauges, and basic controllers.

Now in Part 2, we’re diving deeper into advanced concepts from MurCal’s full product range—J1939 CAN modules, engine controllers, battery chargers, level maintainers, solenoids, and remote monitoring systems—so you can tackle complex systems with total confidence.

Here’s your expanded glossary of key industry terms:

1. Relay Output

An electrically operated switch inside controllers that powers external devices like alarms, pumps, or fuel shutoffs. Relay outputs let engine panels automatically trigger horns, lights, or shutdowns when sensors detect problems.

2. Dry Contact

A simple switch contact with no voltage of its own—just opens/closes circuits. Dry contacts from MurCal gauges wire cleanly into PLCs, annunciators, or remote monitoring without voltage conflicts.

3. 4-20 mA Signal

The industrial standard analog current loop for transmitting pressure, temperature, or level data over long distances. MurCal transducers and transmitters use 4-20 mA for noise-proof communication in harsh oilfield or pump station environments.

4. Digital I/O

Digital Inputs (DI) read on/off states from switches; Digital Outputs (DO) send on/off commands. Found in Enovation engine controllers and J1939 modules, digital I/O automates pump sequencing, fault relays, and remote start/stop.

5. Fail-Safe Circuit

Design where equipment defaults to safe operation if power or sensors fail. MurCal engine controllers use fail-safe logic to shut down engines rather than run blindly during wiring faults or sensor loss.

6. Overcrank Protection

Automatic starter cutoff after failed start attempts. Prevents battery/starter damage on generators and pumps—standard in Series 800 municipal controllers and MurphyLink panels.

7. J1939 CAN Bus

SAE protocol letting modern diesel ECUs talk to displays, controllers, and telematics. MurCal’s PV485-MC displays and S800 panels read RPM, temps, and fault codes directly from Cummins, CAT, and John Deere engines.

8. IP Rating

Ingress Protection code (IP65/IP67) rating dust/water resistance. Higher numbers mean better sealing for marine, irrigation, or oilfield gauges and controllers that face spray, dust, or submersion.

9. Level Maintainer

Automatic oil top-up system for engines/compressors. MurCal’s LM300 series uses float switches to add oil as needed while alarming low/high levels—critical for unattended pump stations.

10. Annunciator Panel

Visual/audible fault display showing which alarm triggered (low oil, high temp, etc.). Tattletale® annunciators use flashing LEDs to pinpoint issues fast during night operations.

11. Battery Charger (Trickle)

Engine start charger maintaining standby generator batteries at peak charge. MurCal’s SENS NRG chargers prevent sulfation—the #1 cause of generator start failures.

12. Magnetic Switch

Sealed glass reed switch activated by magnets—no sparking in explosive environments. Used in oil/gas scrubber levels and Tattletale circuits for reliable, maintenance-free operation.

13. Fuel Shutoff Solenoid

Electromagnetic valve cutting fuel flow on shutdown command. FW Murphy M5081B valves protect engines during faults; governor-mounted kits integrate with electronic controls.

14. Tachometer Pickup

Magnetic sensor near flywheel reading RPM via pulses. Feeds MurCal tachometers and controllers for overspeed protection and hour metering on pumps and compressors.

15. RTD (Resistance Temperature Detector)

Precision temperature sensor using resistance changes. MurCal’s FW Murphy RDT series monitors bearings, exhaust, and compressors with superior accuracy over thermocouples.

Why These Terms Matter

Engineers upgrading control panels, like MurCal’s S800 panels, technicians wiring J1939 harnesses, or OEMs spec’ing irrigation controls—all encounter these terms daily. Understanding them means faster installs, fewer callouts, and systems that actually protect your equipment.

Where You’ll See Them

MurCal’s product pages, FAQs, harness diagrams, Series 800 manuals, and during calls with our tech team. Every term ties directly to real MurCal solutions for municipal, ag, oil/gas, and marine applications.

MurCal’s mission stays simple: rugged instrumentation with expert guidance so your engines, pumps, and compressors run without drama. 

Need help matching these concepts to your next project?

Contact our support team—available Monday-Friday, 8 AM-4:30 PM PT at 661-272-4700 or sales@murcal.com.