We are currently experiencing intermittent issues with the emergency stop and line stop at our facility. The line stop alarm is being triggered even though the button has not been physically pressed. This push button is connected to a digital input module, which is linked to the Simatic ET200 SP system. Despite replacing the NC contact of the push button, the DI module, and verifying the cable, the problem persists. After acknowledging the alarm, we are able to restart the line. This issue reoccurs every 10 to 15 days. Any assistance in resolving this issue would be greatly appreciated.
Are there various line stops or other NC devices connected to this module that can be used to track the loss of an 'on' condition? Does the entire module lose state for all inputs, or just one? Are you monitoring communications on this specific rack? Are the inputs running on AC or DC? What communication protocol (such as Profibus) is used to connect to the rack, and what is the host PLC?
Hello Robert, thank you for your prompt response. We have three line stop NC contact push buttons connected to one DI module. The issue is consistently occurring with one specific button out of the three. It seems that only one input is temporarily losing its state. The circuit operates at DC 24 volts and is hard-wired from the push buttons to the DI module, which is then inserted into the backplane of a Siemens Simatic ET200SP. This ET 200 SP communicates through Profinet (LAN) to the main PLC Simatic S7-1516F. We are using a 7-core x 1 sq.mm control cable that is 30 meters in length for connecting the single-channel line stop and dual-channel emergency stop. Could the cable possibly be causing the issue, or do you suspect a problem with the PLC?
If you are utilizing Profinet communication, errors can result in alarm triggers. It is crucial to ensure that the Profinet cable being used is a professionally built standard Ethernet cable with Profinet RJ45 connectors, utilizing a Profinet cable stripper. Last year, I was contacted by a representative of a German machine builder who was facing intermittent communication errors. Upon inspecting the LAN cable, which was purchased from an office equipment store, I quickly identified the issue. By constructing a cable with a 90 RJ45 plug to minimize stress, I was able to resolve the problem and have not received any further communication regarding errors. This highlights the importance of using the correct equipment and professional assembly to prevent such issues from occurring.
Hello Robert, thank you for your prompt response. We have three line stop NC contact push buttons connected to one DI module. The issue is that the line stop is consistently triggered by the same button out of the three. There is only one input that temporarily loses state and then recovers immediately. This is in a DC 24V circuit, with the push buttons hardwired to the DI module, which is then inserted into the Siemens Simatic ET200SP backplane. The communication from ET 200 SP to the main PLC Simatic S7-1516F is through Profinet (LAN). We are using a 7 core x 1 sq.mm control cable that is 30 meters long for each line stop channel. Could the cable be causing issues, or do you suspect a problem with the PLC? Profinet communication errors trigger alarms, so it's important to ensure that the Profinet cable is a standard Ethernet cable with professionally built Profinet RJ45 connectors. Last year, I assisted a German machine builder who was experiencing occasional communication errors due to using LAN cable from an office equipment shop. Simply touching the cable triggered an alarm. By building a cable with a 90 RJ45 plug to reduce stress, the issue was resolved.
Alfredo Quintero emphasized the importance of using Profinet communication to avoid triggering alarms due to errors. It is crucial to ensure that the Profinet cable is a standard Ethernet cable with professionally built Profinet RJ45 connectors, using a Profinet cable stripper. Last year, a representative of a German machine builder contacted Alfredo regarding occasional communication errors. The machine had LAN cable purchased from an office equipment shop, which triggered an alarm when touched by Alfredo. To resolve the issue, Alfredo built a cable with a 90 RJ45 plug to reduce stress, and there have been no further reports of errors. It is essential to use professional Siemens Profinet RJ45 plugs to maintain smooth communication. If there is a communication issue with the RJ45 plug, it may consistently trigger alarms from the same point, such as the line stop push button.
It seems like you've covered the standard bases - replacing the contact, checking the digital input module, and examining the cable. Since the issue still persists, it might be a software-related glitch. I'd recommend looking into the logs of your Simatic ET200 SP system around the times the emergency stop is triggered. It might provide you with additional insight about any irregularities proceeding the failure. Also, verifying the settings and programming of your control system might help unravel any unexpected behavior. It’s not out of the ordinary for this kind of issue to arise due to a small oversights in the control algorithm.
It sounds like a complicated issue you're dealing with. A possible culprit might be a disruption or fluke in the system's power supply, causing the alarm to be wrongly triggered. You might also want to look into problems at higher levels in the system—maybe it's not a component issue, but something related to the programming of the Simatic ET200 SP system. If it's possible, it might be worth having an expert in these systems take a look. And lastly, is there a correlation with other factory activities when the issue occurs? It could be related to power surges, vibration, temperature variation, etc. These patterns may help in troubleshooting the problem.
Have you considered that the issue could be related to electromagnetic interference? It could be perturbing the input signal of your digital input module, simulating a state that is identical to when the emergency stop is activated. You might want to check for nearby sources of interference and perhaps consider using shielded cabling if you haven't already. Furthermore, the interval of the issue reoccurring every 10 to 15 days seems suspiciously regular. This could potentially point to an external factor at play, perhaps even some form of routine maintenance or operation that's inadvertently introducing the problem.
It sounds like you're dealing with a frustrating intermittent issue! Given that you've already replaced the NC contact and the DI module, I wonder if there might be a software glitch or interference from nearby equipment that could be causing false triggers. It might be worth checking the configuration settings in your Simatic ET200 SP system as well. Sometimes, firmware updates or electrical noise can play a role too, so look into that as well. Keeping a record of any patterns regarding when the alarms trigger could also help in troubleshooting. Good luck!
It sounds like you’ve done a thorough job troubleshooting already, which is frustrating when the problem keeps resurfacing. Given that the issue happens every 10 to 15 days, it might be worthwhile to check for intermittent electrical noise or grounding issues in the system that could be causing the false alarm. Additionally, consider reviewing the program logic associated with the digital input module—perhaps there's a glitch or an edge case that could be triggering the alarm without a physical press. If possible, capturing any related error logs when the alarm goes off might provide more insights into what’s happening. Good luck!
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Answer: Possible causes could include issues with the digital input module, wiring connections, or even software glitches in the Simatic ET200 SP system.
Answer: The user has mentioned that they replaced the NC contact of the push button, the DI module, and verified the cable connections, but the problem still persists.
Answer: The problem reoccurs every 10 to 15 days, according to the provided information.
Answer: The user mentioned that after acknowledging the alarm, they are able to restart the line.
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