# How should I matching the impedance? **URL:** \ **Category:** General Discussion\ **Created:** [August 7, 2019, 9:33am UTC](https://forum.inductiveautomation.com/t/how-should-i-matching-the-impedance/27221 "2019-08-07T09:33:35Z")\ **Posts on this page:** 1\ **Showing post:** 4
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [August 7, 2019, 12:46pm UTC](https://forum.inductiveautomation.com/t/how-should-i-matching-the-impedance/27221/4 "2019-08-07T12:46:36Z")
Impedance matching is a requirement for certain kinds of communications wiring, not 4-20mA loops. Whoever offered that advice is clueless. It is unfortunate that bad advice is mixed with good on the internet, even on this forum, but you get what you pay for. /: However, while it's not an Ignition question, Ignition is pretty popular with engineers who understand such things. And some of us hang out on the forum. (: All that aside, there is an existing topic from @velpandianp. It is inappropriate to repost. Further answers should be over there: > [@1769-IF8 module doesn't read my analog input](http://forum.inductiveautomation.com/t/1769-if8-module-doesnt-read-my-analog-input/27192): > > Hi, We are working with AB-CompactLogix L32E controller including Compact I/O 1769-IF8 analog input module. We have been configure 1769-IF8 module as engineering units (Min 4000 to Max 20000). At the analog input side we have connected Non-Loop powered 4-20mA Amplifier as per 1769-IF8 wiring drawing (Iout+ to Iin+ and Iout- to V/I in-). The amplifier successfully generate the 4-20mA signal without oscillation at the output terminal. But the controller shows only 3200 (engineering unit) value w… --- _[View the full topic](https://forum.inductiveautomation.com/t/how-should-i-matching-the-impedance/27221)._