SeaRAQ 8 Isolated Form A Relay Outputs

Part: 8521   Model: SeaRAQ-8521

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SeaRAQ™ I/O expansion modules provide unprecedented expansion capabilities for Sealevel Relio R3 and Relio R4 industrial computers. The SeaRAQ 8521 expansion board adds 8 isolated relay outputs rated for 5-250 VAC and 5-30 VDC. The Form A relays each have a discrete common and support a maximum 4A current load. The SPST relays are normally open and close when energized.

To protect the host computer from harmful voltage spikes commonly found in industrial environments, the 8521 provides 1500 VAC isolation. For easy, reliable field wiring, the board uses removable, high-retention terminal block connectors.

Sealevel’s SeaMAX software drivers and utilities make installation and operation easy using Microsoft Windows and Linux operating systems. Communicate using industry-standard Modbus RTU protocol or use the Sealevel SeaMAX API software libraries from your application program.

Get a jump start on your digital I/O development with The Digital I/O Handbook that will provide helpful information that you will use again and again. Check out Chapter 1 for an overview of logic principles.


Additional information



Contact Current

2 A Pilot Duty Maximum (per Output)4 A Maximum, Resistive (per Group)

Contact Voltage

5-250 VAC (50/60 Hz)5-30 VDC

Digital I/O

Reed Relay Outputs


PCB is 6.00" (L) x 4.35" (W)

Extended Temperature

Call for Options

Field Wiring

16 – 30 AWG

Humidity Range

10 – 90% Relative Humidity, Non-Condensing


Modbus RTU

Number of Inputs/Outputs

8 Isolated Outputs

Operating Temperature

0°C to 70°C (32°F to 158°F)

Output Isolation

1500 VAC RMS (Field-to-Logic)

Plate Connectors

High-Retention, Removable Terminal Blocks

RoHS Compliant


Storage Temperature

-50°C to 105°C (-58°F to 221°F)

  • Digital expansion module with 8 Form A relay outputs, rated for 5-250 VAC and 5-30 VDC loads
  • Each relay has a discrete common and supports a maximum current load of 4A
  • 1500 VAC field-to-logic isolation
  • Industry standard Modbus RTU interface
  • Input power provided via backplane connector
  • Field wiring is simplified via removable 3.5mm terminal blocks compatible with 16-30 AWG wire
  • Includes 20-position, removable, high-retention Phoenix terminal blocks
  • Sealevel SeaMAX software supports Microsoft Windows and Linux operating systems

Windows Software

Software: SeaMAX - Windows


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