Modicon AS-B814-108 | 8-Channel Isolated Relay Output Module

Description

Modicon AS-B814-108 | 8-Channel Isolated Relay Output Module

Product Introduction

When a legacy Modicon 984 control architecture needs to switch heavy field loads like motor starters, solenoids, or industrial pilot lamps directly from PLC logic, standard solid-state output cards are often vulnerable to high current spikes. The Modicon AS-B814-108 is not a fragile semiconductor output board; it is a heavy-duty 8-channel relay output module engineered specifically to handle punishing industrial loads up to 5.0 Amps per channel. Designed to slide directly into standard Modicon 800-series drop racks, each of the eight output points is completely isolated from the internal backplane bus and neighboring channels via individual relay coils.

Operating at the critical boundary between automated control logic and high-power physical actuators, the module offers high surge-current resilience—though your mileage may vary depending on contact wear from inductive load cycling and cabinet environmental conditions. It keeps older automation systems operating safely without requiring a complete control architecture refit.

AS-B814-108

Key Technical Specifications

Application Scenarios & Pain Points

• Heavy Stamping Press Actuator Control: An automotive plant in the Midwest kept experiencing welded solid-state outputs due to severe inductive kickback from large pneumatic solenoids until swapping in a rugged Modicon AS-B814-108 relay module, which cleanly isolates high-power field loads.
• Municipal Wastewater Treatment Pump Interlocks:
  • Without AS-B814-108: Solid-state switching cards degraded rapidly under continuous heavy motor starter loads, leading to unexpected output dropouts.
  • With AS-: Robust mechanical relay isolation handles high inrush currents effortlessly, ensuring reliable pump sequencing.
• Harsh Industrial Enclosures: Housed inside a high-vibration local control cabinet, the board’s secure card-locking mechanism maintains solid backplane engagement.

QA & Live Testing SOP (Trust Signal)

Legacy relay output cards require thorough mechanical and electrical testing to ensure relay contacts are unpitted and coil circuits switch reliably. Every AS- unit processed through our facility undergoes a strict evaluation protocol:

1. Visual & Contact Inspection: Inspected under magnification for component thermal wear, capacitor health, and board-level trace integrity, alongside checking physical relay block condition.
2. Backplane Bus Verification: Inserted into a Modicon 800-series test rack to confirm proper power rail startup and rack communication handshakes.
3. Relay Contact Resistance & Switching Test: Energized via system logic commands while applying test voltages across all 8 channels to verify clean contact closure, minimal contact resistance, and correct NO/NC jumper path continuity.
4. Protective Packaging: Sealed in heavy anti-static shielding bags and packed in custom cut-foam containers to prevent physical shock during transit.

Field Engineer’s Pitfall Guide

• ❗ Inductive Load Suppression: Always install appropriate flyback diodes across DC inductive loads (like solenoids or DC relays) or RC snubber networks across AC loads. Neglecting suppression will rapidly pit and prematurely wear out the onboard relay contacts.
• ❗ Jumper Configuration Care: When modifying internal jumpers to switch channels from the default Normally Open (NO) state to Normally Closed (NC), ensure power is completely isolated and jumpers are securely seated to prevent intermittent contact behavior.
• ❗ Hot-Insertion Hazards: Avoid sliding modules into live, powered drop racks unless the chassis is specifically rated for hot-swapping, as sparking can damage backplane interface pins.

Intent-Driven FAQ

Can I configure individual channels for both Normally Open and Normally Closed operation?

Yes, the module is user-configurable; it ships default with all channels set to Normally Open (NO), but individual channels can be reconfigured to Normally Closed (NC) by moving the internal circuit board wire jumpers.

Are these units supplied as New Surplus or refurbished working pulls?

We maintain inventory in both factory-sealed New Surplus (NSMP) packaging and thoroughly bench-tested, certified working pulls backed by an extensive operational warranty.

What is the maximum current capacity per output point?

Each of the eight independent relay output channels is rated to handle continuous and surge loads up to 5.0 Amps, making it ideal for driving heavier pilot devices, motor starters, and contactors.

Does the AS- require an external power supply?

While internal logic and relay coil power are driven through the backplane and control logic, the switched power running through the relay contacts to your field devices comes from your independent field power source.