1
\$\begingroup\$

I've never implemented RS422 before (crazy right?). Since the impedance of the line is controlled to 120Ω do I need an impedance controlled connector for that? If anyone has implemented RS422 which connector did you use?

I was thinking I'd use a standard 0.1" connector or a molex connector of simmilar size, would this change the impedance of the line to prevent me from getting the full bandwidth of the RS422 line?

If I remember right on industrial equipment people use screw in terminal connectors.

\$\endgroup\$
12
  • 1
    \$\begingroup\$ I have never faced any issue using just any connectors for RS-422 with standard rates up to 192k. \$\endgroup\$
    – Eugene Sh.
    Aug 2, 2018 at 18:01
  • 1
    \$\begingroup\$ kbits/s.. maybe even up to 250kbits/s if I recall correctly. \$\endgroup\$
    – Eugene Sh.
    Aug 2, 2018 at 18:03
  • 1
    \$\begingroup\$ You might find this topic about impedance of 0.100" headers useful, electronics.stackexchange.com/q/387223/117785 \$\endgroup\$ Aug 2, 2018 at 18:09
  • 1
    \$\begingroup\$ The RS-422 rise time is too large thus the connector spacing is insignificant and will not affect overall signal because there is insufficient bandwidth to detect it. \$\endgroup\$ Aug 2, 2018 at 18:15
  • 3
    \$\begingroup\$ expected rise time >10ns at source with a wave velocity of >20 cm/ns will NOT affect impedance even at 20Mbps. \$\endgroup\$ Aug 2, 2018 at 18:25

1 Answer 1

1
\$\begingroup\$

I've never seen 0.1 or Molex used for RS-422, although I did see screw terminals. I don't think you'd achieve "full bandwidth of the RS422 line", which is 10Mbps over 50 feet, using these connectors.

AFAIK most people use EIA-449/EIA-530 as guidelines for 37, 25 or 9-pin D-SUB.

\$\endgroup\$
2
  • 3
    \$\begingroup\$ 0.1" 2x5 headers are successfully used in all USB 2.0 (480 Mbps) connections to front panels on desktop PC and towers. \$\endgroup\$ Aug 2, 2018 at 19:38
  • \$\begingroup\$ Hmm.. true that. Well, maybe it will work. FWIW CAT6 + DB9/25 combination works despite cable impedance mismatch, although I never tried this above 1Mbps or over 25m \$\endgroup\$
    – Maple
    Aug 2, 2018 at 20:06

This site is temporarily in read-only mode and not accepting new answers.

Not the answer you're looking for? Browse other questions tagged .