An offpage connector is a functional symbol commonly used in schematic capture software.
Offpage connectors basically help to "clean up" the appearance of the schematic by allowing complex
circuits to be broken up across several sheets or pages.
There are three types of offpage connector:
- Input, indicated by ->*, where the asterisk designates the point of connection.
- Output, indicated by *->
- Bidirectional, indicated by *< ->
In general, input offpage connectors are placed on the left side of the page, whereas output
connectors are placed on the right. Bidirectional signals can (and do) appear on either side
of the page. Usually, there will be many offpage connectors on a schematic representing a
circuit containing at least one large integrated device, such as a CPLD or FPGA.
In order to connect signals across schematic sheets, it is necessary simply to name the net
associated with the offpage connector. For instance, you could have a signal called "TCK", that
would begin at a clock source and end at a JTAG interface. If you wanted to have the clock
source and IC with the JTAG interface on different pages, you would attach an "out" offpage
connector to the source and an "in" offpage connector to the destination. You would then label
the wire attached to each offpage connector "TCK". That way, the schematic software will see
the interface between the two devices as a single, unbroken wire.