Customer Value & Operational Benefits

Group Isolation for Mixed Sources

The biggest practical advantage of the ​ is the two isolated groups. We frequently use Group A for “Clean” 240V AC signals (like panel lamp test switches) and Group B for “Noisy” 240V AC (like contacts switching inductive loads, e.g., solenoid valves or starter coils). Because the groups are optically isolated from each other, a voltage spike or common-mode shift on Group B won’t false-trigger or damage the inputs on Group A. This allows you to mix different power sources (e.g., Utility A for Group A, Generator B for Group B) on the same module safely.

Hardware Filtering for Contact Reliability

Mechanical relay contacts and limit switches bounce. The ​ has a fixed RC filter network that establishes a 20ms debounce time. You don’t need to write timer logic in the PLC to stabilize a rattling limit switch; the module filters it at the hardware level. This keeps the %I table clean and prevents the CPU from seeing rapid 0-1-0-1 transitions that could cause false trips or erratic counter increments in the logic.

Distributed Mounting Flexibility

Being part of the Field Control series, the ​ doesn’t force you to home-run 16 pairs of 240V AC wire back to a central control room PLC rack. You mount the IC670 station near the equipment (e.g., a pump skid or conveyor tail end), run short wires to the , and connect the BIU back to the main CPU via a single multi-conductor cable (or fiber optic link for long distances). This reduces wire spend, voltage drop on long 240V runs, and electromagnetic interference (EMI) pickup.

Field Engineer’s Notes (From The Trenches)

The most common failure mode I see with ​ is “One Group Dead.” An input on Group A works, but Group B is dark (LEDs off, logic 0) even though 240V is across the field device.

Check the external AC power to the group. Unlike 24V DC modules where power is often bussed on the backplane or a single terminal, the ​ requires you to land 240V AC L and N specifically for Group A (Terminals usually A1/A2) and Group B (B1/B2). If a fuse blows on the panelboard feeding Group B, or the neutral lug loosens on that terminal block screw, that whole group of 8 inputs goes dead. The “PWR” LED on the module will stay green (because BIU power is fine), misleading you into thinking the module is fully powered.

Also, tighten those terminal screws. The 240V AC terminals handle low current (mA), but corrosion builds up on aluminum wire or tinned strands over time, increasing impedance. I’ve seen “failing” inputs that were just loose terminal block screws causing a high-resistance connection—the voltage sagged to 140V under load, below the 155V threshold.

Real-World Applications

• Motor Control Center (MCC) Auxiliary Contacts: The ​ (Group A) wires to the “Run” and “Fault” auxiliary contacts (240V AC coil voltage) of 10 RVSS starters in a pump house. The BIU sends the status to the main RX3i CPU, allowing the SCADA to show “Pump 1 Running” without running 240V AC wire 500 feet back to the main panel.
• Conveyor Safety Interlocks: Mounted in a local NEMA 4X box on a sorting conveyor, the ​ (Group B) picks up 240V AC signals from pull-cord e-stops and guard door limit switches. The 20ms filter rejects noise from the adjacent 480V VFD power feeders, ensuring the “E-Stop Latched” input is solid.

High-Frequency Troubleshooting FAQ

Verify the external 240V AC power​ to the input groups. The “PWR” LED only indicates the 5V logic power from the BIU is present. If you forgot to land the 240V AC L/N wires to the terminal block (or the breaker for that supply is tripped), the input circuits have no reference voltage to detect the field devices. Check for 240V AC between the Group A power terminals and Group B power terminals on the block with a DVM.

No. The ​ is a 240V AC module (155-265V AC operating range). 120V AC (typically 110-132V) is below the “Off-state” threshold (40V) but also below the “On-state” threshold (155V). The module will not recognize 120V as a valid “On” signal. You need the IC670MDL240​ (120V AC version) for 120V devices.

Why do my inputs flicker On/Off rapidly?

This is usually electrical noise or a floating neutral. The ​ has a 20ms filter, but if you have long untwisted wires running parallel to VFD output cables, induced voltage can cross the 40V threshold. Ensure you use twisted pair​ for the field wiring (even for AC inputs) and that the 240V AC neutral is solidly grounded at the service panel. If the noise is severe, a snubber circuit (RC across the contact) might be needed on the offending device.

No. The IC670 Field Control stations (BIU and I/O modules) do not support hot-swapping. You must power down the IC670 station (or at least the specific power supply feeding that module’s group if externally fused) before removing or inserting the . Failure to do so can cause arcing on the backplane connector or damage the opto-isolators.

Please note:​ The listed price is not the actual final price. It is for reference only and is subject to appropriate negotiation based on current market conditions, quantity, and availability.