Key Technical Specifications
- Product Model: LC82*A
- Manufacturer: YOKOGAWA Electric Corporation
- Product Type: RL-BUS Interface Card
- Network Protocol: YOKOGAWA RL-BUS (Real-time Local Bus)
- Target System: MOPS-P221*C/EKMU/2-RL Operator Station
- Associated Cards: DP88B*A (Display), CP81D (Processor)
- Bus Topology: Multi-drop / Bus Network
- Mounting Style: PCB Backplane Slot
- Application: Distributed Control System (DCS) Communication
- Status: Legacy / Discontinued Spare Part
Product Introduction
When an RL-BUS interface card dies in a legacy YOKOGAWA DCS, the operator station goes blind. You aren’t just replacing a piece of silicon; you are restoring the critical link between the control room and the plant floor. The LC82*A is exactly that link. It serves as the RL-BUS interface card for the MOPS-P221C operator station, translating network traffic so the display and processor cards can actually do their jobs.Engineers hold onto these because finding a working RL-BUS card today is like finding a needle in a haystack. It doesn’t have flashy specs because it’s a legacy part, but it reliably handles the physical bus communication required to keep older YOKOGAWA DCS systems alive. Just be aware that this specific revision can be extremely sensitive to bus termination and grounding issues. If your RL-BUS is noisy, this card will be the first to throw faults, even if the card itself is perfectly fine.
Quality SOP & Tech Pitfalls
We don’t just pull these out of a box and ship them. Every LC82*A goes through a strict QA protocol before it leaves our facility. We start with a visual and counterfeit check under magnification to ensure no fake YOKOGAWA logos or reworked solder joints. Next, it goes on a live test rack where we verify RL-BUS communication handshakes and check for excessive heat draw. Finally, we run insulation resistance checks with a Fluke 115 and log the exact firmware/hardware revision before sealing it in anti-static packaging.Here is the brutal reality check: Do not assume an LC82*A is an exact drop-in for an LC82*B without verifying the backplane and firmware. I once saw a tech swap an LC82A into an LC82B slot, and the RL-BUS locked up solid for six hours because of a subtle hardware revision difference in the bus transceiver. Also, always photograph your jumper settings and verify the RL-BUS termination resistor is still on the board before you blame the new card.
Installation & Configuration Guide
- Pre-Installation: ⚠️ SHUTDOWN FIRST. Do not hot-swap this card. Power down the operator station, wait 5 minutes for capacitors to discharge, and take high-resolution photos of the old card’s jumpers and wiring.
- Removal: Label every cable connected to the RL-BUS interface. Release the DIN clips or backplane ejectors safely. Do not force the card; if it sticks, check for hidden mounting screws.
- Installation: Copy the DIP switch and jumper settings exactly. This step prevents 90% of startup failures. Align the LC82*A with the backplane guides and press firmly until fully seated. Reconnect the RL-BUS cables exactly as photographed.
- Power-On & Testing: Restore 24V DC power. Watch the LED boot sequence. If the RL-BUS link LED doesn’t illuminate within 30 seconds, check your termination and cabling before assuming the card is dead. Download or verify the operator station configuration once the hardware link is stable.
Compatible Replacement Models
| Compatibility Tier | Model | Notes |
|---|---|---|
| ⚠️ Hardware Mod Required | LC82*B | Newer revision. May require backplane updates or firmware changes. Verify with YOKOGAWA docs before swapping. |
| ❌ Hardware Mod Required | LC83*A | Different bus architecture. Requires full system upgrade, not a direct swap. |
Frequently Asked Questions (FAQ)
Can I hot-swap the LC82*A while the operator station is running?
Absolutely not. This is a legacy RL-BUS card, not a modern hot-swappable I/O module. Pulling it live will crash the operator station network and could fry the backplane transceivers. Always do a controlled shutdown.Is the LC82A a direct replacement for the LC82B?
Tread carefully here. They share the same form factor, but internal transceiver revisions differ. I’ve seen them work interchangeably, and I’ve seen them cause bus lockups. Always check your system’s hardware manual or call the OEM to verify cross-compatibility for your specific firmware version.The RL-BUS link LED is blinking red after installation. Is the card bad?
Probably not. A blinking red LED usually means a physical layer issue, not a dead card. Check your RL-BUS termination resistor (it must be at the end of the bus), verify your shield grounding, and ensure the cable isn’t pinched. Only replace the card if you’ve verified the bus integrity.Are these cards brand new or refurbished?
The LC82*A has been discontinued by YOKOGAWA for years. True factory-sealed new units are essentially unicorns. Most available units are “New Surplus” (old stock, never used) or professionally refurbished. Always ask the supplier for the exact condition and warranty terms before buying.How do I know if my RL-BUS network is failing before the card dies?
Watch for intermittent operator station freezes, dropped tags, or communication timeout alarms in the DCS. RL-BUS cards usually fail gracefully, but the network degrades first. Use a YOKOGAWA bus analyzer or oscilloscope to check for signal reflections and noise before you start throwing parts at the problem.Does this card require a specific YOKOGAWA software license?
No. The LC82*A is purely a hardware interface card. It doesn’t hold the operator station license or the control logic. However, replacing it may require you to re-initialize the RL-BUS node in the system configuration software, which does require engineering access.
