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Product Description

The Model 121 Dual RS-232 to RS-422 converter module contains two independent and programmable converters, each equivalent to the Model 63-2, mounted on a plug-in card for use with the Model 76-2 card cage. This provides space efficient rack mounting of up to 28 converters in 5.25" of vertical rack space. Each converter performs the function of providing a hardware conversion for full duplex signals between devices containing RS-232 and RS-422 I/O ports. Each converter is equipped with a DTE/DCE selector switch which reverses pins 2 and 3 of the RS-232 connector. A programmable cable termination resistor provides the flexibility of mating with various cables. Each converter has a built-in Loopback Switch and Transmit Data and Receive Data Indicators. The Loopback Switch causes the internal circuitry to be "looped" from the normal output back to the input to confirm the total operation of the internal circuitry. It also loops back the output lines so that a loopback test can be performed from the far end, thereby, testing the link lines.

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