Abstract: A device, including at least one tube/relay plug, at least one printed circuit board connector and an interface board, uniquely designed to adapt a printed circuit card for connection to at least one tube/relay socket. The tube/relay plug and the printed circuit board connector are attached to the interface board such that the pins of the plugs extend in one direction and the connector opens in the opposite direction. The interface board is provided with electrical conductors connecting the plug and the connector. One or more card guide means may be attached to the interface board for facilitating insertion of the printed circuit card into the connector and for supporting the card when it is in position.

Abstract: An improved system and method for transmitting and monitoring, for example, commands to relays or other output command devices driving controlled devices remotely located from the transmission portion of the transmission and monitoring system. The system is usually divided into two parts geographically separated by a significant distance with two wires running between the parts. The first part is used for transmitting the command and interrogation signals through the use of current levels set by overall circuit characteristics and produced on alternate positive and negative half cycles by an alternating current source and set by the resistive load in the loop. The second part is for interpreting the signal by relay discrimination to determine if it is a command or just the interrogation signal requesting the current state of the device being controlled by the system and also for local indication.

Abstract: An improved system and method for transmitting and monitoring, for example, commands to relays or other output command devices driving controlled devices remotely located from the transmission portion of the transmission and monitoring system. The system is usually divided into two parts geographically separated by a significant distance with two wires running between the parts (FIGS. 1 and 3). The first part is used for transmitting the command and interrogation signals through the use of current levels set by overall circuit characteristics and produced on alternate positive and negative half cycles by an alternating current source and set by the resistive load in the loop. The second part is for interpreting the signal by relay discrimination to determine if it is a command or just the interrogation signal requesting the current state of the device being controlled by the system and also for local indication.