The best replacement for rs232 is rs485.

The best alternatives to rs232 are rated as following:
★★★★★  rs485
★★★★  rs422
★★★★  usb
★★★  db9
★★★  ttl
★★  rs232c
★★  uart
★  null modem
★  rj45
★  gpib
★  spi
★  serial port
★  i2c
  can bus
  485
  rs530
  max232
  rs 422
  rs 485

Your alternative for rs232 is not listed? Suggest!
Speaking about rs232, one probably shouldn't forget about labview.

Other search terms related to rs232 and their ratings are:
★★★★★ labview
★★★ max232
★★★ pic16f877
★★ hyperterminal
You have in mind a companion for rs232 and it is not yet here? Propose!



Google Trends

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rs232
rs485
rs422