20
© Sealevel Systems, Inc. eI/O Manual | SL9221 01/2023
170 DESCRIPTION (CONT)
The optically isolated digital inputs featured on the 170 are designed unlike the opto-inputs found on many
other Sealevel products. The 170 provides a voltage to the opto input, which is current limited with a 330
ohm resistor. Connecting either of the inputs to a common pin will cause current to flow through the opto-
isolator, activating the input.
The inputs were designed this way, so the end-user does not need to provide a voltage source. A simple
external contact closure is all that is required to trigger the input.
Two common pins are provided with the optically isolated inputs for convenience; however, both
common pins of the inputs are electrically equivalent on the board.
The diagram below shows how the inputs are intended to be used.
Relay Outputs
Type
2 SPST solid state relays
Power
DC 150W
Contact Voltage
60VDC max
Contact Current (DC)
2.5A max.
Digital Inputs
Type
2 Dry Contact Sensing
Isolation
1000VDC
Source Current
12mA max
