Abstract: A dual piston pilot valve includes a housing forming first and second cylinders. A first spool is moveable in the first cylinder for engaging the a piston to effect movement of the first piston and a second spool is moveable in the second cylinder for engaging a second piston to effect movement of the second piston. The valve further includes a single pressurized fluid supply port communicating with both the first and second cylinders, a first output port communicating with the first cylinder, a second output port communicating with the second cylinder, a single exhaust port communicating with both the first and second cylinders, and a diaphragm engaging the housing and both the first and second pistons. The diaphragm is positioned between both the first and second spools and both the first and second seal regions of the first and second pistons to effect a seal between the single exhaust port and the first and second spools.

Abstract: An electro-pneumatic control system pneumatically connected to a pressure source and electrically connected to an electrical signal source includes a selector switch having an electrical input connected to the electrical signal source, and having a first electrical output and a second electrical output. The system further includes a body having a movable member positioned therein, wherein the body has a first port and a second port; a first regulator valve having a bidirectional port connected to the first port of the body, having an input port connected to the pressure source, having an exhaust port, and having an electrical actuator connected to the first electrical output of the selector switch; and a second regulator valve having a bidirectional port connected to the second port of the body, having an input port connected to the pressure source, having an exhaust port, and having an electrical actuator connected to the second electrical output of the selector switch.

Abstract: A serial transmission system for controlling a network of input/output devices is provided. The serial transmission system includes: a three wire serial link; a master unit for controlling communication over the serial link; multiple input remote units for receiving information from the input devices; and multiple output remote units for controlling the output devices. The master unit includes a programmable optically isolated microcontroller adapted to initiate a synchronous data link control (SDLC) communications protocol with the remote units. In addition the master unit includes memory tables for storing input/output, error, diagnostic, status and node availability information. This information can be shared with a PC or host controller. In addition, the PC or host controller can include programs for directing the master unit and remote units to initialize, reset, scan, or maintain an idle condition.