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3. Key Technical Specifications
| Parameter | Value |
|---|---|
| I/O Configuration | 8 Digital Inputs (DI) + 8 Digital Outputs (DO) |
| Communication Interface | RS-485 |
| Operating Voltage | 24 VDC (±10%) |
| LED Indicators | HEALTH, ALARM, POWER, CONTROL |
| Mounting | DIN rail or cabinet slot |
| Dimensions (approx.) | 230 × 150 × 60 mm |
| Weight (approx.) | 0.8 kg |
| Compatibility | Native with CCC IOC-555 series controllers |
| Diagnostics | Watchdog timer + front-panel status LEDs |
| Typical Use | Compressor start/stop, valve position feedback, protection interlocks, status monitoring |
4. Product Introduction
The Compressor Controls Corp IOC-555-D REV (17-550555-001) is a simplex digital I/O card built as an expansion module for CCC IOC-555 series controllers. It supplies eight discrete inputs and eight discrete outputs for field signal interfacing in industrial compressor packages.
The card reads on/off signals from switches and sensors while driving relays, solenoids, and contactors for start/stop, load/unload, and interlock functions. RS-485 provides the link to the host controller. Front-panel LEDs and a watchdog timer support basic self-diagnostics. It is widely applied in oil & gas, petrochemical, and process compressor control systems. Always match the exact revision marking and verify pinout against the existing installation documentation before replacement.
IOC-555-D REV
IOC-555-D REV
5. Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| POWER LED off | Missing or reverse-polarity 24 VDC | ✅ High | Measure 24 VDC at power terminals with correct polarity | Confirm supply voltage and wiring before replacing the card |
| HEALTH LED flashing + ALARM LED on | Communication fault or self-test failure | ✅ High | Inspect RS-485 wiring, termination, and address conflicts; power-cycle the card | Check cabling and controller configuration; replace if fault remains after power cycle |
| Digital outputs do not energize | Loose DO wiring, missing load power, or failed channel | ✅ High | Measure voltage at DO terminals under active command; verify load supply | Confirm controller logic and field wiring; replace card if channel is dead |
| Inputs not detected | Open DI wiring or failed field device | ✅ Medium | Force a known-good contact at the DI terminals and observe status | Trace field devices and wiring first; the card is rarely the first failure point |
| Intermittent communication | Noise on RS-485 bus or address conflict | ✅ Medium | Verify shielding, termination resistors, and unique addressing | Improve grounding/shielding; ensure only one device occupies each address |
| Card healthy but system still alarms | External process or controller logic issue | ❌ Low | Review controller diagnostic buffer and field device status | Problem is usually upstream of the I/O card |
If basic LED and voltage checks do not isolate the fault, photograph the board (including revision markings), LED states, and connectors, then contact technical support with the serial number and system details.
6. Frequently Asked Questions (FAQ)
Q: Is this unit new original or refurbished?
A: New Original / New Surplus. Units receive visual inspection, power-up verification, and basic communication checks. Test photos and reports are available on request.
Q: What does “Simplex” mean on the IOC-555-D REV?
A: It is a non-redundant I/O card. It prioritizes unidirectional command flow from the controller to the field devices and is not intended for dual-redundant hot-standby architectures.
Q: How many digital channels does it provide?
A: Eight digital inputs and eight digital outputs. It is a discrete-only card for switches, relays, and solenoids. It does not include analog channels.
Q: Will it work with non-CCC controllers?
A: It is natively designed for CCC IOC-555 series controllers. Connecting to third-party systems normally requires an external RS-485-to-Modbus converter plus configuration. Plug-and-play operation is limited to the CCC platform.
Q: Can I hot-swap the card?
A: No. Power the system down completely before removing or installing the card. Hot-swapping risks damage to the board or backplane.
Q: What should I verify before installing a replacement?
A: Photograph the existing card’s revision markings, connector orientation, and any address or jumper settings. Match the part number and revision as closely as possible. Confirm 24 VDC supply capacity, RS-485 polarity, termination, and shielding. Verify the controller I/O map matches the new card.
Q: What is the typical operating temperature range?
A: Standard industrial range is approximately 0 °C to 55 °C. Some installations support extended ranges with derating. Always confirm against the specific revision documentation and your cabinet conditions.
