PC Remote I/O Family Overview


Connecting the PC to the Remote Family of interfaces is simple. A single 4-wire serial RS422 cable is daisy-chained from the PC to each interface. Up to 63 interfaces of any combination of functions can be connected to a single RS422 channel. The PC could use a RS422 converter on its RS232 comm port or add a RS422 interface card.


Each interface contains an on-board switching power regulator. Therefore, a higher voltage can be daisy-chained to the remote interfaces keeping the current requirements low and the remote voltages stable. For example, if all the interfaces combined used 10 amps at 5 volts (50 watts), then the current required from a 24vdc supply would be 2.45 amps (58.8 watts) for 85% efficiency. Wire sizes are smaller and voltage variations are not a problem.


Each remote interface has a special wiring base and plug-in logic module. The DIN rail mounted wiring base contains the necessary touch-safe terminal strips along with the necessary jumpers to select address and optional features. The active components are contained in the logic module. The logic module plugs into the screw-down connector on the wiring base. No jumpers or adjustments are needed on the logic module. This makes field replacement easy and safe. Simply remove the module and insert a new one. No wires need to be removed and no jumpers or adjustments need to be done.


The 115.2 KBAUD communication rate and simplified protocol make data transfer fast. Typically, 5 bytes are required to request (or send) data to an interface. Since no gaps or filler bytes are needed between different interface addresses, the average time per interface is 5 bytes or 434 usec.

A 10-module system could be continually updated every 4.34 milliseconds. Critical data could be addressed in an interleave fashion, or a second dedicated RS422 port could be used.

Remote I/O | Remote Encoder Input | Remote Analog Input | Remote Analog Output | Remote Stepper Output

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Phocus Systems Inc.
P.O. Box 16160
Seattle, Washington 98116
Tel: (206) 972-0931