4 wire vs 2 wire 4-20ma loop question

ganutenator · Jun 25, 2017

Mickey said:
Maybe a picture will help a little.

Grounding the power supply is optional. ( I don't, but there are other treads for that debate)

that makes sense. thanks

ganutenator · Jun 25, 2017

Tom Jenkins said:
This isn't a stupid question. Many people have been confused by 2-wir vs. 3-wire vs. 4-wire. I always make sure I cover this in my classes.

Note that many transmitters are 4-wire because the power draw is too high to take it from the 4-20 mA loop. Many 4-wire transmitters are AC powered.

how did i miss this.
i usually see tom jenkins and go straight to that ****.
dude, this is awesome.

ganutenator · Jun 25, 2017

Tom Jenkins said:
This isn't a stupid question. Many people have been confused by 2-wir vs. 3-wire vs. 4-wire. I always make sure I cover this in my classes.

Note that many transmitters are 4-wire because the power draw is too high to take it from the 4-20 mA loop. Many 4-wire transmitters are AC powered.

nice to see you still around. you were the sh_t back in 2000 even.

Bit_Bucket_07 · Jun 25, 2017

ganutenator said:
actually, this was the possibly the best answer thus far. would love to see the electronic diagram though.

Mine would be identical to Mickey's. Only the loop powered, 2 wire transmitter is connected in series with the analog input.

danw · Jun 25, 2017

Some confusion may occur when determining whether a field device (transmitter) is 2, 3 or 4 wire because of the number of wires/conductors in an M12 cordset, however, it is not the number of wires/conductors in a cordset that determines 2, 3, or 4 wire functionality.

2, 3, or 4 wire functionality is determined by the minimum number of wires/conductors required for 4-20mA functionality (by industry norm terminology).

A cordset may have more wires/conductors than are needed for 4-20mA functionality for other functions, but those conductors do not count when determining 4-20mA functionality.

Bit_Bucket_07 · Jun 25, 2017

danw said:
Some confusion may occur when determining whether a field device (transmitter) is 2, 3 or 4 wire because of the number of wires/conductors in an M12 cordset, however, it is not the number of wires/conductors in a cordset that determines 2, 3, or 4 wire functionality.

2, 3, or 4 wire functionality is determined by the minimum number of wires/conductors required for 4-20mA functionality (by industry norm terminology).

A cordset may have more wires/conductors than are needed for 4-20mA functionality for other functions, but those conductors do not count when determining 4-20mA functionality.

I don't really see how cordsets are relevant to the discussion, since most field instruments don't even connect to a controller via a cordset. Electrical circuits are electrical circuits, regardless of the method of termination.

Tom Jenkins · Jun 25, 2017

ganutenator said:
how did i miss this.
i usually see tom jenkins and go straight to that ****.
dude, this is awesome.

Glad to help!

danw · Jun 25, 2017

Bit_Bucket_07 said:
I don't really see how cordsets are relevant to the discussion, since most field instruments don't even connect to a controller via a cordset. Electrical circuits are electrical circuits, regardless of the method of termination.

See this thread's post #1: "banner ultra sonic sensor. Had to connect the brown to 24+, blue to 24-, the black to 24- and the return (white) to the input card."

Banner ultrasonic's that I've seen use M12 cordsets and the wire colors match Banner cordsets.

It's relevant because the stated problem involves a device with an M12 cordset.

ganutenator · Jun 25, 2017

tom jenkins showed up. this sh_t solved.

ganutenator · Jun 25, 2017

i need to hire 15 of him btw.

AustralIan · Jun 26, 2017

You should be able to list PLCtalk.net user names in the 'desired candidate attributes' section of Job ads, some with "NOT" in front of them

.

ganutenator · Jun 26, 2017

AustralIan said:
You should be able to list PLCtalk.net user names in the 'desired candidate attributes' section of Job ads, some with "NOT" in front of them .

my name would most def. have a not in front of it then.

but in real life, i never had a failed project in over 21 years.
in fact, i was the dude that fixed other people's failed projects.

but we all here trying to get better.

never stop learning.

4 wire vs 2 wire 4-20ma loop question

ganutenator

Lifetime Supporting Member

ganutenator

Lifetime Supporting Member

ganutenator

Lifetime Supporting Member

Bit_Bucket_07

Member

danw

Lifetime Supporting Member

Bit_Bucket_07

Member

Tom Jenkins

Lifetime Supporting Member

danw

Lifetime Supporting Member

ganutenator

Lifetime Supporting Member

ganutenator

Lifetime Supporting Member

AustralIan

Member

ganutenator

Lifetime Supporting Member

Similar Topics