We are currently experiencing issues with a vacuum pressure sensor that has malfunctioned. Unfortunately, the original model is no longer available, but the manufacturer has provided us with a replacement sensor from Festo. After installing the new sensor, the Human-Machine Interface (HMI) is displaying a pressure reading of 145 mBar while the machine is stationary and not generating any vacuum. When we disconnect the pressure sensor from the analog input, the output correctly shows 0 volts, which accurately corresponds to a vacuum measurement down to -1 Bar, resulting in a 10-volt output. However, when checking the voltage on the analog input card with the sensor disconnected, we observe a reading of 2.3 volts. Initially, we suspected that the new sensor might be defective, but after testing it on another machine, we obtained identical results. This situation has led us to consider compatibility issues, despite assurances from Festo that we were using the correct replacement unit. To clarify, we reached out to the machine manufacturer, who confirmed that the output type should be configured as 0-10V, which is already set correctly. To troubleshoot the situation further, we connected the old type sensor from our second machine to the first machine, and all readings on the HMI were accurate. We would appreciate any suggestions on how to resolve this issue or any additional checks we should perform. Attached is an image of the input connection details for the machine. The input card in use is a Siemens 6ES7134-4FB52-0AB0, located within an ET200 remote rack. Your assistance in diagnosing this problem would be greatly valued.
Are the measurements on the old unit identical to those on the new unit?
Indeed, both units operate within a 0-10V range and measure pressure from 0 to -1 Bar.
Please provide both the old and new sensor type numbers. It's likely that the Festo is configured for 2-10 Volt or possibly 4-20 mA. Additionally, verify that the 0 Volt connection is correctly established.
Updated Component: FESTO SDE1-V1-G2-HQ4-C-P2-M8 New Component: FESTO SPAU-V1R-H-G18FD-L-PNLK-PNV It seems that the original unit lacks configuration options for its output. In contrast, the new model offers three output configurations, and we have opted for the 0-10V setting. Please note that I have not evaluated the output of the original sensor when it is disconnected from the PLC.
CRMCC stated that when measuring the voltage on the analog input card with the sensor unplugged, a reading of 2.3V is observed. Can you clarify the specific points between which you are measuring to obtain a notable voltage on an unconnected input?
It sounds like you've done a thorough job of troubleshooting so far! Given that the old sensor works fine on the first machine and the new one shows consistent readings across different setups, I would recommend checking for potential grounding issues or interference on the analog input line. Sometimes, even slight variances in wiring or connections can lead to unexpected voltage readings. Additionally, since you're dealing with a compatibility issue, it might be worth double-checking if the new sensor requires any specific calibration or settings adjustments in the HMI beyond what you initially set. If everything seems okay, exploring Festo's technical support for any firmware or compatibility notes could also provide some insights. Good luck, and keep us updated!
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