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Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
Details
This is a "full" serial port that can be electronically configured to work in RS232,
RS422, or RS485 mode. The Tibbit is based on the Sipex SP337 universal
transceiver.
Galvanic isolation is achieved by using ISO7141 and ISOW7842 digital isolators
manufactured by Texas Instruments (ISOW7842 also generates isolated power).
These isolators create a separate power domain containing the SP337 transceiver,
surrounding circuitry (not shown on the diagram), and the terminal block connector.
Due to the isolation, the ground pin (pin 5) of the terminal block is not connected to
the system (CPU) ground and exposes the ground of the isolated domain instead. All
I/O lines on the terminal block connector are also from this isolated domain. The
need to route an isolated ground to the outside world is why this Tibbit is