Build your own RS232 adapter with LED indicators - Do It Easy With ScienceProg
Amazon.com: Gearmo USB to Serial RS-232 Adapter with LED Indicators, FTDI Chipset, Supports Windows 11/10/8.1/8/7/, Mac OS X 10.6 and Above : Electronics
4 Channel Digital LED Light Source with RS232 Control – Inosaki
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EZSync RS232 Mini Tester with LED Indicators, DB9 Male to DB9 Female, EZSync911 – Serial Connections Made Easy
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USB Serial - USB 2.0 RS232 Adapter with LED Indicators
16in. USB 2.0 to RS-232 Serial Converter w/ LED Indicators & FTDI