RS-232 Breakout RIN1 signal appearing on ROUT2 instead of ROUT1

TECHNICAL SUPPORT Communication Modules
1

Customer:

I’m wiring up RS-232 Breakout boards and encountering strange behavior: when I send a signal over RIN1, it comes out through ROUT2, not ROUT1. I swapped for a second board and then get output from both ROUT2 and ROUT1. I need to know if this is a quirk of the chip (MAX232EC) since I’m prototyping with the breakout boards before designing a custom PCB using this chip. Is the internal wiring of the chip incorrect, or is the MAX232E datasheet out of date?

Originally submitted via email support on 10 April 2026. Migrated to the forum for community visibility.

2

Soldered Support:

The board is labeled correctly and no signals have been swapped. The connector layout has RIN2 and OUT2 on the same connector, which is intentional and matches the design. This is not an issue with the internal wiring of the MAX232 chip or an outdated datasheet.

Attachment omitted in migration: RS232 Transceiver breakout Schematic.pdf

Attachment omitted in migration: Screenshot 2026-04-13 at 10.42.02.png