Rugged Ethernet IO Device with 4 Integrated Controllable Relays​

Ethernet IO - Smart 4 Relay Output
Smart 4 Relay Output

Ethernet I/O

RLH Smart SeriesThe Smart Relay Output is an Ethernet device with 4 Integrated controllable relays. The device allows for web based control of the relays and may be integrated into distributed control and network management systems to allow those systems to controlled it’s Relays. Each of the Relays can be individually configured to send customized emails and notifications when an event is triggered. The device supports a wide variety of protocols it is compatible with over Ethernet. Integration options supported are: SNMP Polling and Traps, Modbus TCP featuring addressable registers, and DNPv3 TCP for integration with utility and other automation control systems.

Contact Closure Over Ethernet

The RLH Smart Relay Output may be paired with an RLH Smart Input Sensor. When using RLH’s System Link feature, the two devices become linked establishing a tunnel over an Ethernet network and will transport a digital outputs being received by the Input Sensor through the Ethernet tunnel to the linked Relay Output device. The System Link feature can be set up via: One to One, Many to One, and One to Many allowing for event distribution and consolidation as needed.

View the matching Smart 4 Input Sensor


  • Rugged Design – Operating temperature, -40°C ~ 70°C
  • Intuitive embedded web interface for configuration
  • 4 Relay Outputs for initiating alarms or actions though one of it’s integrated protocols
  • Supports SNMP 1, 2c, 3, & SNMP Traps 1, 2c
  • Supports DNP 3.0 over Ethernet
  • Supports Modbus over Ethernet
  • Use the System Link feature to Pair this device with an input sensor device for alarm transportation over Ethernet
  • Event Consolidation, Send alarms from up to 4 locations to 1 Relay Output device
  • Email alarms for the Outputs are customizable to your application
  • Advanced SMTP integration allowing for SSL and TLS based authentication
  • Event log with time stamps
  • Relays can support up to 60 watts for most voltages
  • System power ranges available: 24-48VDC or 125VDC
  • PoE Powered device – Can be powered by any IEEE 802.3af compliant PoE source
  • 10/100 Fast Ethernet Port
  • Limited Lifetime Warranty
  • Made in USA

Powering Voltage:
Standard Model – 24-48VDC
-A Model – 125VDC
-B Model – 12VDC

PoE Powered Device:
IEEE 802.3af compliant (Compatible with mode A & B PoE sources)

Power Consumption:
6 Watts (Maximum)

Protocols Supported:
DNP 3.0 TCP, Modbus TCP, SNMP Polling 1,2c,3, SNMP Traps 1, 2c, SMTP w/ TLS Authentication

System Link Response Time:
Typical 8ms, Maximum 45ms
One-To-Many (UDP) < 15ms Many-To-One (TCP) < 250ms

*Specifications listed are based on direct connections. Network overhead should be considered when calculating overall system response times.

Data Interface:
Ethernet (RJ-45)

Data Rate:
Fast Ethernet 10/100Mbps

Relay Outputs 1~4:
SM-OUT4-NO-XX-2 – Normally Open Relays
SM-OUT4-NC-XX-2 – Normally Closed Relays

Relay Maximum Ratings:
115VAC / 1.08A / 125VA
12VDC / 3.00A / 36 Watts
24VDC / 2.50A / 60 Watts
48VDC / 1.25A / 60 Watts
130VDC / 0.46A / 60 Watts
220VDC / 0.27A / 60 Watts

LNK – System Link ON/OFF Status
Outputs – ON/OFF Status

System Alarm Output:
NO/NC Relay

Surge Protection:
Varistors & Automatic resettable fuses
DC Input Isolation 1.5kV
Voltage Reversal Protection

Powder coated steel and aluminum alloy
Physical Dimensions H 4.93” x W 1.20” x D 3.93” (125mm x 31mm x 100mm)

Mounting Style:
Standard DIN rail (T-35)
Wall Mount

Temperature -40°F to +158°F (-40°C to +70°C)
Humidity 95%
MTBF 175,000 Hrs. (Circuit Board level)

General Information Miscellaneous
Contact Closure over Ethernet - One to One (TCP)
Contact Closure over Ethernet – One to One (TCP)
Contact Closure over Ethernet - One to Many (UDP)
Contact Closure over Ethernet – One to Many (UDP)
Event Consolidation - Many Inputs to One Output
Event Consolidation – Many Inputs to One Output
Remote Relay Control
Remote Relay Control


Lead Time: 1 Week*

For product questions, volume pricing and/or delivery outside of the US and Canada, please contact sales.


Smart 4 Relay Output

Product configurationOutputsOutput TypePart numberPrice
4 Relay Outputs, Normally Open4 Relay OutputsNormally OpenSM-OUT4-NO-2$395.00
4 Relay Outputs, Normally Closed4 Relay OutputsNormally ClosedSM-OUT4-NC-2$395.00
  • For the 125VDC input power option, please note your part number, add -A to the end, and get your quote here
  • For the 12VDC input power option, please note your part number, add -B to the end, and get your quote here.

Smart 4 Input Sensor

Product configurationInputsInput TypePart numberPrice
4 Digital Inputs, 24-48VDC Digital Inputs4 Digital Inputs24-48VDCSM-IN4-48-2$395.00
4 Digital Inputs, 3-15VDC Digital Inputs4 Digital Inputs5-15VDCSM-IN4-12-2$395.00
4 Digital Inputs, Dry Contact Sensing Inputs4 Digital InputsDry Contact SensingSM-IN4-DR-2$395.00
  • For the 125VDC input power option, please note your part number, add -A to the end, and get your quote here
  • For the 12VDC input power option, please note your part number, add -B to the end, and get your quote here.

*Lead times are estimates and may vary. You will be contacted within 1 business day to go over the details of your order. If you require a specific date, let us know!
*Days = Business Days

WarningWarning: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to

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