Hello, I am working with a compact Logix PLC and my current project involves setting up alarms in our SCADA system for when an analog signal becomes stagnant. Typically, the analog signal should be trending upward, but if it goes out of range and stops moving, I need to configure a trigger in the PLC to send an output. This output will then be transmitted to our SCADA system as an alarm, indicating that there is an issue with the input that needs attention. Thank you.
The user Ones_Zeros inquired about setting up alarms in a compact Logix PLC to monitor when an analog signal stops moving. Typically, the analog signal trends upward and if it reaches a certain level or stops moving, how can one configure the PLC to trigger an output? This data can then be fed into a SCADA system to alert of any issues with the input. Additionally, a stagnant analog signal could also indicate a potential leak.
Ones_Zeros inquired about setting up alarms in a compact Logix PLC to alert the SCADA system when an analog signal stops moving. The goal is to trigger an output in the PLC when the analog signal deviates from its normal upward trend. To achieve this, you can compare the current analog input value with a stored value, initiate a timer if they are equal, and generate an alarm when the timer expires. It's also important to periodically update the stored value with the current analog input to enable continuous monitoring. Consider incorporating deadbands to account for any drift in the analog input. This process will help identify any issues with the input and prompt timely action.
To ensure critical system reliability, I suggest setting up redundant sensors connected to separate analog input modules in the PLC. Establish a tolerance between the two sensor readings. If the difference exceeds this tolerance, an alarm will be triggered to signify a potential sensor or module failure. This method has proven successful for many of my clients. Create two tags named OLDINPUT_1 and OLDINPUT_2 to store the sensor readings. Compare the new sensor values to the saved values at set intervals. If the new values are not greater than the saved values, trigger an alarm. If both new values are greater, update the OLDINPUT tags. Repeat this process regularly. Always set up and trigger alarms within the PLC, and display them on the HMI interface. It's also advisable to log these alarms for reference and analysis.
Looking for an Anti-Stall Timer? Set up a timer based on your alarm time setting. Monitor the analog values during each scan to check for any discrepancies with the last recorded value. If the values are not equal, the timer will reset. Make sure to account for variations in the analog signal by setting a tolerance or deadband range. If the timer reaches completion, an alarm condition will be triggered. Don't forget to update the last recorded analog value each scan.
Attention "Beer_and_popcorn" Bros! You are invited to apply your algorithms to the blue curve. I propose the following algorithm: At the beginning, the ancillary variable is calculated as the measured value minus the noise amplitude (peak to peak). During each scan, if the ancillary variable is less than the measured value, the ancillary variable is adjusted by adding the slope factor (per scan time); otherwise, an alarm is triggered. If the difference between the measured value and the ancillary variable is less than the noise amplitude, the ancillary variable is set to the measured value minus the noise amplitude. The distribution mode is determined to be half of the slope factor.
Hey there! You can achieve this by configuring a rate-of-change alarm in your PLC program. Essentially, this program will track the difference in your analog signal over a certain timeframe. If the difference is zero or negligible (adjustable threshold), it could trigger an output. In other words, you'd be monitoring the rate at which your analog signal changes, and if it falls below a certain rate, you'll know it's stagnant. Make sure to account for the inherent noise in the signal to avoid false triggers. Just double-check the PLC and SCADA system compatibility for seamless alarm transmission. Good luck!
I've worked on something similar before and from that experience, I'd suggest incorporating a timer in your PLC program which starts when the analog signal value stays stagnant for a designated threshold time. The moment it crosses this specified duration, you can then set the alarm bit which would be monitored by the SCADA system. To ensure that the process runs efficiently, remember to reset the timer whenever the signal value begins to change again. Hope this helps and best of luck with your project.
✅ Work Order Management
✅ Asset Tracking
✅ Preventive Maintenance
✅ Inspection Report
We have received your information. We will share Schedule Demo details on your Mail Id.
Answer: 1. How can I set up alarms in SCADA for stagnant analog signals in a Logix PLC? - To set up alarms for stagnant analog signals in a Logix PLC, you need to configure a trigger in the PLC to send an output when the analog signal becomes stagnant. This output will be transmitted to the SCADA system as an alarm, indicating an issue with the input.
Answer: - Setting up alarms for stagnant analog signals in SCADA helps in detecting when an analog signal stops moving or goes out of range, indicating a potential issue that requires attention. This proactive approach enables timely intervention to prevent or address problems.
Answer: - Configuring triggers in a Logix PLC to detect stagnant analog signals involves setting up logic that monitors the trend of the analog signal. When the signal becomes stagnant or goes out of range, the trigger activates to send an output, which is then communicated to the SCADA system as an alarm.
Answer: - To ensure the reliability and effectiveness of alarms for stagnant analog signals in SCADA, it is important to regularly monitor and test the alarm configuration. Additionally, setting appropriate thresholds and response mechanisms in both the PLC and SCADA system can enhance the accuracy and responsiveness of the alarms.
Join hundreds of satisfied customers who have transformed their maintenance processes.
Sign up today and start optimizing your workflow.