[?]: s7 200 analog signal is unstable

SIMATIC S7-200/300/400, Step7, PCS7, CFC, SFC, PDM, PLCSIM,
SCL, Graph, SPS-VISU S5/S7, IBHsoftec, LOGO ...
kambiz
Posts: 121
Joined: Sat Dec 09, 2006 5:04 am
Location: Iran

[?]: s7 200 analog signal is unstable

Post by kambiz »

hi
i need some advice, so help me if someone can!

i use analog input AIW0 from analog module EM235. Signal on the input AIW0 is 0(4) ... 20 mA (0...32000), but that signal is unstable!
Coyote
Posts: 41
Joined: Wed Sep 06, 2006 10:07 am
Location: Slovenia

Post by Coyote »

So, what's up. You should make the signal stable, there is no other way. You can also apply filter for analog signals (see the system block).
dsekulic
Posts: 186
Joined: Sun Feb 12, 2006 5:47 pm
Location: Europe

Post by dsekulic »

Hi,
Maybe You have some interference in vicinity of measuring system. Do You You use screened cable?
regards
xdoit
Posts: 36
Joined: Wed Nov 21, 2007 2:13 pm
Location: China

Post by xdoit »

hi,
You should use STP (Shielded Twisted Pair) cable for that sensor and make sure only one end to be connect to earth.

rgds,

hsiung