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F-DI Error

Created by: hgq at: 5/21/2008 6:08 AM (9 Replies)

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5/21/2008 6:08 AM	Rate (0)
hgq Posts: 83 Rating: (1)	Hello, I have a F-FH set up and from time to time receive spurious trigger signals causiningunnecessary shut down. CPU: 414-4HJ04-0AB0 V4.0 F-DI: 326-1BK01-0AB0 F monitoring time setting: 2500 ms; Evaluation of sensors: 1oo2 evaluation; Type of sensor interconnection: 2 channel equivalent; Behavior at discrepancy: Supply last valid value; Discrepancy time: 10 ms. Physically one dry contact is parallely connected to both left channel and right channels. CPU Diagnostic message: Event ID: 3942; Module fault present; Input address: 56; Channel information available; Internal module error; External module error; Channel error detected; Alarm in rack 1; Requested OB: Diagnostic interupt OB (OB 82); Priority class : 25; External error: incoming event (time, date) I am not able to get online help since the set up is far away. Have tried Siemens web via keying in "3942" only got the F-DI manual. Could not found the event 3942 from this manual. Any help could be appreciated. Thanks in advance. hgq
hgq Posts: 83 Rating: (1)
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5/21/2008 1:00 PM	Rate (0)
Mario Braganca Posts: 124 Rating: (17)	I'm not sure if I understand correctly you problem so I'l talk based on my understanding. Here are some sugestions: 1. If it's a Fail-Safe System , it's supposed to behave like it's planned. So it must cause a shutdown in case of one senson fails (1oo2). 2. If you have only one sensor the project concept is wrong because the sensor is less reliablethan the CPU. You must study the whole Safety Loop and not only the CPU alone. This includes Sensor and Final Control Elements. If you don't consider this your loop will not get SIL2 or SIL3. Look EXIDA site (http://www.exida.com/software/exsilentia.asp) for SIL calculation tools. 10 ms is probably too small. I suggest you to increase this time and use two reliable sensors. If you want to increase availibility (keeping safety) you could use a 2oo3 votation F-Block. Regards Mario
Mario Braganca Posts: 124 Rating: (17)
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5/22/2008 4:42 AM	Rate (0)
hgq Posts: 83 Rating: (1)	Hello Mario, Thanks for the help, your advise will be taken care of. I am investigating what has heppened to the system and would like to know what does error code "3942" mean. Any idea? Regards, hgq
hgq Posts: 83 Rating: (1)
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5/22/2008 5:50 AM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 11/4/2024 Posts: 12293 Rating: (2690)	Hello hgq; (Hex)3942 is an error code that s generated by the operating system of your CPU when a generic "Module Error" is detected; it is used to call OB82. See the attached list of Asynchronous Errors from the System and Standard Functions manual. Hope this helps, Daniel Chartier Attachment AsyncErrorCodes.jpg (381 Downloads)

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5/22/2008 6:06 AM	Rate (0)
hgq Posts: 83 Rating: (1)	Thanks dchartier. Have a nice day! hgq
hgq Posts: 83 Rating: (1)
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5/23/2008 8:19 AM	Rate (0)
Sevab-Peter Advanced Member Joined: 12/20/2005 Last visit: 11/5/2024 Posts: 30 Rating: (1)	Hello hgq, As far as I can see the setup is indeed in error. The system expects two physical conatcts. It performs a short circuit test at certain intervals and detects the parallell connection as a short circuit betweeen the two channels and ends up with hardware error. And as Mario says the safaty level is then also derated with only one contact. Regards /Peter

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5/23/2008 10:25 AM	Rate (0)
hgq Posts: 83 Rating: (1)	Hi Sevab, Thanks forinfomation. If I understand correctly, the safety integrity level does not depand on the numbers of contact being checked for each signal. Please find attachment (abstracted from sheet 82 of 198, Siemens manual S300f_e.pdf), in which only single contact is usedhoweverthissetupcould achieve SIL3. Regards, hgq Attachment F-DI Setup.pdf (407 Downloads)
hgq Posts: 83 Rating: (1)
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5/23/2008 11:03 AM	Rate (0)
hgq Posts: 83 Rating: (1)	Hello, May i change my question for this issue. Firstly please open the attachment, in which there is two typical setups. Setup 1. Single contact connected to oppsing channels; Setup 2. Dual contact respectively connected to oppsing channels. In setup 1, the discrepancy time between both channels merely depens on the response time difference between left channel and right channel. According to hardware manual, the response time is maximum 3 ms, either from "0" to "1" or from "1" to "0". Therefore the maximum discrepancy time is 3 ms. It should be reasonable to assume that the discrepancy time is nearly zero since the left channel and right channel are in the same module and both are electronic. In setup 2, the discrepancy time depends on the mechanical reation of both contacts, which may be significant comparing to setup 1. My arguement is In setup 1, 10ms for discrepancy timeremaining as default is sufficient. In setup 2, the setting for discrepancy time can be bigger depanding on the mechanical reaction of both contact and the application requirement. Is thisanalyzingcorrect? Regards, hgq Attachment 1 contact & 2 contacts.pdf (434 Downloads)
hgq Posts: 83 Rating: (1)
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5/26/2008 1:23 PM	Rate (0)
Sevab-Peter Advanced Member Joined: 12/20/2005 Last visit: 11/5/2024 Posts: 30 Rating: (1)	Hello hgq, Your analyze seems correct to me. It seems that the single contact is a redundant sensor, and if it fulfills SIL 3 it could be OK. The problem I have exiprienced with two contacts is that the system detects a short circuit between the channels when connecting them like this. There is a setting to deactivate the short circuit test in the hardware configuration. It can sometimes be useful, but beware if it changes the safety level of the system when deactivating it. /Peter

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5/27/2008 5:40 AM	Rate (0)
hgq Posts: 83 Rating: (1)	Hello, I would appreciate more comments from safety experts. Thanks hgq
hgq Posts: 83 Rating: (1)
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