ECM P/N 5033 provides eight channels of RS485 / RS422 I/O. The 110 ohm termination for each channel is enabled or disabled in software. Disabling termination saves power by eliminating unneeded or redundant termination. Speeds of up to 20 Mega bits per second are possible, but this design also features a 250K bits per second slower edge rate mode. The 250K bit mode is valuable when EMI is more of a concern and throughput is not important. All channels power up as inputs with the outputs disabled.

In the example below a Technobox P/N 4988 breakout panel provide two 9 pin d-sub connections for RS485 channels. Each 9 pin d-sub carries four RS485 pairs and a ground. Note that a pair of ports of the Technobox P/N 4988 breakout panel is in use, allowing other ECMs to use the remaining six 9-pin d-sub connections. A serial identification circuit prevents use with incorrect FPGA IP. Other RS422/485 usages include military, medical, transportation and industrial control systems.

Datasheet http://www.technobox.com/Datasheet-ECM-5033-Interface-4pgv1-A80401-press.pdf

micro mezzanine system electrical conversion module RS485 / RS422 8 channels programmable termination Technobox 5033