Expanding board (cape) for Beaglebone black contains four serial ports RS232. Board can be used everywhere you need to communicate with a few different devices via serial port. Board contains real time clock, time is set properly without internet connections.
More about the cape:
Blog: Cape 4 × RS232 for Beaglebone black
HOBRASOFT-4x232-00A0.dts - firmware source for board 4x232, GPL License
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