The 582-10 detects presence of data on a main (Data 1) and secondary (Data 2) data channel by detecting positive level transitions on both inputs. If no data is detected on the Data 1 channel for 1 to 9 minutes (adjustable in 1 minute increments), an alarm will occur causing the switch to transfer the Data 2 channel to the SELECTED DATA output. If the Data 2 channel also has an alarm, no switching will occur or switching can always be forced to the Data 2 channel. After switching to the Data 2 channel, when the Data 1 channel alarm clears the switch transfers data back to the Data 1 channel. Switching is accomplished using a relay. If power is removed from the 582-10, a jumper selects signal continuity from either the Data 1 or Data 2 channel to the SELECTED DATA output. The channels can be manually switched by closures to ground. The PC power supply provides power to the 582-10. External redundant DC can be used. The unit is housed on a 3/4 size PCI card.