Each ISD Series product consists of 4 intrinsically safe inputs and 4 corresponding electromechanical relay outputs. With input voltage applied, the V LED will be ON (GREEN) to indicate power is applied. When the input device is closed, the input LED is ON (GREEN). When the output relay is energized, the output LED is ON (ORANGE). ISDUM4 has an eight-position DIP-switch with configurations applied independently to each channel. Configurations applied: Standard Logic (DIP Switch set to “STD”): When the input device in the hazardous area is closed, the corresponding output relay is energized. When the input device opens, the corresponding output relay will de-energize. Inverse Logic (DIP Switch set to “INV”): When the input device in the hazardous area is open, the corresponding output relay is energized. When the input device closes, the corresponding output relay will de-energize. No Time Delay (DIP Switch set to “0 S”): The output relay will have an immediate change in status in response to the input device closing or opening. Fixed 2 Second Delay (DIP Switch set to “2 S”): The output relay will delay 2 seconds before a change of status in response to the input device closing or opening.