4-20mA
- Thread starter grankin
- Start date
ArikBY
Member
Hi
Its depend on some things:
What is the resolution of your analog card.
What type of PLC you use.
Please provide more info.It would help us to help you.
Its depend on some things:
What is the resolution of your analog card.
What type of PLC you use.
Please provide more info.It would help us to help you.
YOU CAN DO ONE THING THAT,
you scale the level probe 0mA = 0
20mA = 1000
and then in the logic you do like this
for example you are working with PL7PRO
take an operator and do like this
%mf1000:=int_to_real(MOD(YOUR INPUT CHANNEL - 1000)
HOPE YOU WILL GET THE INVERSE
BALAMURALI
you scale the level probe 0mA = 0
20mA = 1000
and then in the logic you do like this
for example you are working with PL7PRO
take an operator and do like this
%mf1000:=int_to_real(MOD(YOUR INPUT CHANNEL - 1000)
HOPE YOU WILL GET THE INVERSE
BALAMURALI
rdrast
Lifetime Supporting Member
Here is an excellent thread on scaling, by a local (to PLCS.NET) Guru...
http://www.plctalk.net/qanda/showthread.php?t=15069
That should answer any question you may have.
http://www.plctalk.net/qanda/showthread.php?t=15069
That should answer any question you may have.
Tom Jenkins
Lifetime Supporting Member
Ron's post is the best theroretical explanation I've seen. Here is a simple example:
Problem: SCALE TANK LEVEL in range of 0 to 1000 gallons
Assume Analog Input range is 0 to 32767 counts
Scale to: 0 = 0 gal, 20 ma = 1000 gallons
Slope = Scaled Maximum - Scale Minimum / Input Max - Input Min
Slope = (1000 - 0) / (0 - 32767) = -0.0305185
Offset = Scaled Min - (Input Min X Slope) = 0 - (32767 X -0.0305185) = 1000
Scaled value = (Input value x Slope) + Offset
Scaled value = Signal Input x (-0.0305185) + 1000 = -0.0305185 X Signal Input + 1000
Assume Analog Input range is 0 to 32767 counts
Scale to: 0 = 0 gal, 20 ma = 1000 gallons
Slope = Scaled Maximum - Scale Minimum / Input Max - Input Min
Slope = (1000 - 0) / (0 - 32767) = -0.0305185
Offset = Scaled Min - (Input Min X Slope) = 0 - (32767 X -0.0305185) = 1000
Scaled value = (Input value x Slope) + Offset
Scaled value = Signal Input x (-0.0305185) + 1000 = -0.0305185 X Signal Input + 1000
Similar Topics
Hi all,
I'm connecting several 4-20mA sensors together in parallel (only one shown below) The enclosure is ABS plastic with metal backplate
DAQ...
Problem:
Our PLC can only output 4-20mA, but the actuators it needs to control, modulate based on a 0-135Ohm signal. Buying 4 or 8 individual...
What's your go to 4-20ma isolator. I've got some 4 wire 4-20ma from several flow meters and scales that I would like to isolate before it gets to...
Hi,
I need to read three 4-20mA signals from a DCS(ABB) in a remote 6 channel analog input module with RS485 modbus port.
When I connected...
Hello this is my first post. Looking forward to being more involved in this community to learn and hopefully help others.
Any help or guidance...