Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Fluctuating Analogue Reading on HMI

Created by: Engineer Ghulam at: 5/7/2013 10:13 AM (7 Replies)

Rating (0)

Thanks 1

8 Entries

5/7/2013 10:13 AM	Rate (0)
Engineer Ghulam Regular Member Joined: 1/22/2013 Last visit: 11/20/2024 Posts: 3 Rating: (0)	Dear Sir, Have a good day. I am using Siemens s7-1200 PLC and KPT1000PN HMI screen. I am using it for water treatment industry. My analogue module is 0-20mA and signal coming from sensor is 4-20mA. So I done current scaling, then I normalized and scaled this analogue value to get my results. I am showing this value 'pH' on HMI screen. Problem is value fluctuating very much and secondly there is not same value as I getting on my transmitter screen. On transmitter and HMI screen value should be same. Let say my pH value is 6.8, which transmitter is showing good and stable value, but on HMI screen it is fluctuating form 5-8, which is wrong value also unstable. Attached is the way how I programmed my analogue input. Output of the 'SCALE-X' block is tagged to HMI, which you can see in attachment. I tested both data types ''int' and' Uint (word)' for analogue input, but same result. grounding is done properly, unused inputs/outputs are shortcircuted and tranmitter is sending true/stable value to the PLC. I think i have to design a filter for the analouge input to make it more stable, i do not know how to make a filter...or is there any other solution? Attachment Analouge Input.pdf (516 Downloads)

Suggestion To thank Quote Answer

5/7/2013 10:46 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/19/2025 Posts: 6858 Rating: (1366)	Engineer Ghulam Dear Sir, Have a good day. I am using Siemens s7-1200 PLC and KPT1000PN HMI screen. I am using it for water treatment industry. My analogue module is 0-20mA and signal coming from sensor is 4-20mA. So I done current scaling, then I normalized and scaled this analogue value to get my results. I am showing this value 'pH' on HMI screen. Problem is value fluctuating very much and secondly there is not same value as I getting on my transmitter screen. On transmitter and HMI screen value should be same. Let say my pH value is 6.8, which transmitter is showing good and stable value, but on HMI screen it is fluctuating form 5-8, which is wrong value also unstable. Attached is the way how I programmed my analogue input. Output of the 'SCALE-X' block is tagged to HMI, which you can see in attachment. I tested both data types ''int' and' Uint (word)' for analogue input, but same result. grounding is done properly, unused inputs/outputs are shortcircuted and tranmitter is sending true/stable value to the PLC. I think i have to design a filter for the analouge input to make it more stable, i do not know how to make a filter...or is there any other solution? Hello, Normally, smart transmitters have signal processing options such filtering.You can check the manual of transmitter and also checking the following previously discussed topic on TIA Portal: Input a filter on the analog input to reduce instability Best regards Hamid Hosseini
	Demo Channel on Youtube
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users realpower_ir

5/7/2013 1:16 PM	Rate (0)
Bryll Posts: 168 Rating: (5)	Here's a little something I made once for a Mitsubishi PLC system that I also made up for the Siemens project I have. Don't really know how to export functions from the software, but I tried to create a library and made a "save as" to my desktop. I hope you can open it It's a homemade scale function, where you can set the "min" and "max" values of your incoming analog signal. You can also select the range of the sensor by setting the "min" and "max" levels of the output signal. The output is in INT and REAL values. There's no filter function built in, but you should be able to correct your engineering value with this. Best of luck Attachment Own_LIbrary.zip (360 Downloads)
Bryll Posts: 168 Rating: (5)
Suggestion To thank Quote Answer

5/7/2013 1:58 PM	Rate (0)
BryanG2001 Posts: 113 Rating: (22)	If the analogue signal is moving a lot it may not be a programming error, more likely a problem with the 4-20mA loop. Does your sensor have an active or passive 4-20mA output? Is the common, the DC negative line, common to both sensor and PLC? Does the sensor have an isolated output? Generally you fix this kind of problem by adding a loop isolator.
BryanG2001 Posts: 113 Rating: (22)
Suggestion To thank Quote Answer

5/10/2013 1:52 PM	Rate (0)
Engineer Ghulam Regular Member Joined: 1/22/2013 Last visit: 11/20/2024 Posts: 3 Rating: (0)	sensor have 2 wire passive 4-20mA current output......also sensor is connected in loop power supply....sensor is showing data on a transmitter that is generating signal which is fed to analouge input of PLC...

Suggestion To thank Quote Answer

5/10/2013 9:28 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/24/2025 Posts: 15558 Rating: (2468)	Engineer Ghulam I tested both data types ''int' and' Uint (word)' for analogue input, but same result. grounding is done properly, unused inputs/outputs are shortcircuted and tranmitter is sending true/stable value to the PLC. I think i have to design a filter for the analouge input to make it more stable, i do not know how to make a filter...or is there any other solution? The analog outputs should not be wired to M (ground/common), just the unused inputs. What is the analog input hardware configuration for filtering? Maximum, or the default?
	science guy
Suggestion To thank Quote Answer

3/23/2020 7:31 AM	Rate (0)
AutoGen_3073689 Posts: 1 Rating: (0)	Engineer Ghulam Dear Sir, Have a good day. I am using Siemens s7-1200 PLC and KPT1000PN HMI screen. I am using it for water treatment industry. My analogue module is 0-20mA and signal coming from sensor is 4-20mA. So I done current scaling, then I normalized and scaled this analogue value to get my results. I am showing this value 'pH' on HMI screen. Problem is value fluctuating very much and secondly there is not same value as I getting on my transmitter screen. On transmitter and HMI screen value should be same. Let say my pH value is 6.8, which transmitter is showing good and stable value, but on HMI screen it is fluctuating form 5-8, which is wrong value also unstable. Attached is the way how I programmed my analogue input. Output of the 'SCALE-X' block is tagged to HMI, which you can see in attachment. I tested both data types ''int' and' Uint (word)' for analogue input, but same result. grounding is done properly, unused inputs/outputs are shortcircuted and tranmitter is sending true/stable value to the PLC. I think i have to design a filter for the analouge input to make it more stable, i do not know how to make a filter...or is there any other solution? Hi, Any update on this issue. I am also facing same problem. please help me to resolving this issue.
AutoGen_3073689 Posts: 1 Rating: (0)
Suggestion To thank Quote Answer

3/23/2020 8:25 AM	Rate (0)
Prof. Frink Platinum Expert Joined: 7/5/2013 Last visit: 1/16/2025 Posts: 3123 Rating: (518)	Hi, AutoGen_3073689 Hi, Any update on this issue. I am also facing same problem. please help me to resolving this issue. what kind of cable are you using? Regards, Frink
	Pi is exactly three! All you have to do is think of things which people need but which don’t exist yet.
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on