You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old September 5th, 2005, 08:02 AM   #1
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Water meter & PLC

I have water meter equiped with optoelectronic pulser as follow:
Switch type: IR reflex light barrier to DIN 19234; plug-in design
Switch voltage: 8.2 VDC
Switch current: < 1.2 mA
Quiescent current: > 2.1 mA
Can I wire the pulser output directly to PLC input 24VDC?
Any suggestion will be appreciated.
  Reply With Quote
Old September 5th, 2005, 09:16 AM   #2
randylud
Member
United States

randylud is offline
 
randylud's Avatar
 
Join Date: Oct 2002
Location: Greensboro,NC
Posts: 933
24V dc
1746-IB8 Input 8 Current Sinking DC Input 19

24V dc
1746-IB16 Input 16 Current Sinking DC Input 19

24V dc
1746-IB32(1) Input 32 Current Sinking DC Input 19

24V dc
1746-ITB16 Input 16 Fast Response DC Sinking Input 19

24V dc
1746-IV8 Input 8 Current Sourcing DC Input 22

24V dc
1746-IV16 Input 16 Current Sourcing DC Input 22

24V dc
1746-IV32(1) Input 32 Current Sourcing DC Input 22

24V dc
1746-ITV16 Input 16 Fast Response DC Sourcing
Specification Catalog Number
1746-IB8 1746-IB16
(RTB)
1746-ITB16
(RTB)
(Fast Response)
1746-IB32
(1)

Voltage Category
24V dc sink

Operating Voltage
10 to 30V dc sink 15 to 30V dc at 50C sink

15 to 26.4V dc at 60
C sink

Number of Inputs
8 16 16 32

Points per Common
8 16 16 8

Backplane
Current Draw
5V dc
0.050A 0.085A 0.085A 0.050A

24V dc
0.0A 0.0A 0.0A 0.0A

Signal Delay (max.)
on = 8 ms

off = 8 ms
on = 8 ms
off = 8 ms
on = 0.3 ms
(2)

off = 0.5 ms
on = 3 ms
off = 3 ms
Off-State Voltage (max.)
5V dc 5V dc 5V dc 5V dc

Off-State Current (max.)
1 mA 1 mA 1.5 mA 1.6 mA

Nominal Input Current
8 mA at 24V dc
Specs are the answer my friend, you can get them for all of the AB discrete I/O modules by going to AB.com and looking them up. If you are using some other brand, then do the same thing on their site. As you can see, the switching voltage ranges for these 24V modules would not suit your 8.2VDC device. Maybe another module would be more appropriate?

__________________
Thunder is good, thunder is impressive; but it is lightning that does the work!
Mark Twain-8/28/1908
  Reply With Quote
Old September 6th, 2005, 07:16 AM   #3
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Thank you randylud.
Anyone could give me informatin source regarding IR reflex light barrier to DIN 19234 (namur)?
Thank you in advance.
  Reply With Quote
Old September 6th, 2005, 08:31 AM   #4
JesperMP
Lifetime Supporting Member + Moderator
Denmark

JesperMP is offline
 
JesperMP's Avatar
 
Join Date: Feb 2003
Location: Copenhagen.
Posts: 13,220
It is an "Optoelectronic IR reflex light barrier".
But the voltage and current specs seems to indicate that it mimics a NAMUR type sensor.
So you need a NAMUR/DC converter to get the signal into the PLC.
__________________
Jesper
3 strikes and you're out
  Reply With Quote
Old September 7th, 2005, 06:53 AM   #5
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Thank you JesperMP.
Anybody know device that could convert from NAMUR level to PLC 24VDC logic?
With thanks.
  Reply With Quote
Old September 7th, 2005, 07:05 AM   #6
JesperMP
Lifetime Supporting Member + Moderator
Denmark

JesperMP is offline
 
JesperMP's Avatar
 
Join Date: Feb 2003
Location: Copenhagen.
Posts: 13,220
PR Electronics has the 2288 module that converts/isolates between many different signal levels incl. NAMUR. I use it myself.
There is an additional nifty "pulse stretching" function that may be useful if the impulse from the sensor is so short that the PLC cannot pick it up.
Tip: Put the converter locally in a terminal box if the cable runs are very long. Otherwise it will pick up noise and convert it to false signals.
__________________
Jesper
3 strikes and you're out
  Reply With Quote
Old September 7th, 2005, 11:16 AM   #7
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Thank you JesperMP again.
Cause you deal with this kind of sensor, can I wire the sensor as the attached image?

  Reply With Quote
Old September 8th, 2005, 02:19 AM   #8
JesperMP
Lifetime Supporting Member + Moderator
Denmark

JesperMP is offline
 
JesperMP's Avatar
 
Join Date: Feb 2003
Location: Copenhagen.
Posts: 13,220
I never try to do like that. From where did you get that diagram ?

I know that NAMUR defines a supply voltage (8.2V) and OFF and ON levels in current (1.2mA and 2.1mA).

I guess that the diagram applies to a particular kind of PLC input card. I doubt that it will work everywhere.
Some counter inputs will accept a NAMUR sensor directly.
__________________
Jesper
3 strikes and you're out
  Reply With Quote
Old September 9th, 2005, 05:00 PM   #9
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Jesper,
The diagram was drawn by me, it is for any traditional 12-24VDC PLC input which has the following specifications:
ON Current/Voltage Level: >5mA/10VDC
OFF Current/Voltage Level: <0.5mA/<2VDC
From the diagram: 24V=8.2V+10V+5mA*R
R=1.16K
IOW, R will achieve ON current>2.1mA and 8.2V
I am not satisfied if it will work or may damage the sensor and/or PLC input!
What is your opinion and advice.
With thanks
  Reply With Quote
Old September 13th, 2005, 06:35 AM   #10
JesperMP
Lifetime Supporting Member + Moderator
Denmark

JesperMP is offline
 
JesperMP's Avatar
 
Join Date: Feb 2003
Location: Copenhagen.
Posts: 13,220
hashem,
I have absolutely no idea if it will work or not.
I would not waste any time but get an signal conditioner that is designed to do the job.
But I am not you.
__________________
Jesper
3 strikes and you're out
  Reply With Quote
Old September 13th, 2005, 07:27 AM   #11
OkiePC
Lifetime Supporting Member
United States

OkiePC is offline
 
OkiePC's Avatar
 
Join Date: Mar 2005
Location: ENE of Nowhere Oklahoma
Posts: 9,781
Hashem, In a circuit designed like that, wouldn't you have to consider the input impedance of the PLC card in the calculation for R1?
  Reply With Quote
Old September 13th, 2005, 08:44 AM   #12
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Thank you OkiePC,
The PLC input as the following diagram still work ON/OFF logically.

I am not satisfied if I add the pulser it will work or may damage the sensor and/or PLC input!
What is your opinion and advice.
PLC input impedance: 1.8K @12-24VDC
With thanks
  Reply With Quote
Old September 13th, 2005, 09:00 AM   #13
hashem
Member
United States

hashem is offline
 
Join Date: Aug 2005
Location: anytown
Posts: 33
Sorry! the diagram is:
  Reply With Quote
Old September 13th, 2005, 10:11 AM   #14
OkiePC
Lifetime Supporting Member
United States

OkiePC is offline
 
OkiePC's Avatar
 
Join Date: Mar 2005
Location: ENE of Nowhere Oklahoma
Posts: 9,781
I agree with Jesper. Get a signal isolator/conditioner designed for your sensor. I don't think a simple voltage divider circuit will do what you intend without risk to the sensor.
  Reply With Quote
Old April 29th, 2013, 11:56 PM   #15
boxofrelays
Member
United States

boxofrelays is offline
 
boxofrelays's Avatar
 
Join Date: May 2003
Location: Kailua, Oahu, Hawaii
Posts: 56
Here's a link discussing signal isolation to a NAMUR standard signal

LINK to Tekron

If you're device is in a hazardous area, then use intrinsically safe barriers that limits the current going to the sensor.

Non-hazardous? You can use a simple non-isolating interface by using a single, general purpose, 2N2222 transistor to interface an 8-volt NAMUR device and connect directly to a 24-volt PLC input.

Here is a good resource on simple transistor circuits:

LINK PCB Heaven

Hope this helps.

-Chris
__________________
Systems Integration Group, Inc.
Kailua, Hawaii 96734

Last edited by boxofrelays; April 30th, 2013 at 12:10 AM.
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
PC to PLC Protocol TheRixta LIVE PLC Questions And Answers 13 December 17th, 2008 12:56 PM
Simulator, Simulation, Shadow Code Terry Woods LIVE PLC Questions And Answers 1 January 2nd, 2005 01:40 PM
PLC to PLC Communication (Mitsubishi FX2N) c0met LIVE PLC Questions And Answers 6 May 31st, 2004 07:31 PM
plc for prover meter emegawe LIVE PLC Questions And Answers 1 September 12th, 2003 07:38 PM
PLC hook up check LIVE PLC Questions And Answers 10 July 31st, 2003 01:26 AM


All times are GMT -5. The time now is 04:33 AM.


.