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| 7/9/2009 1:59 PM | |
Joined: 11/14/2008 Last visit: 5/6/2024 Posts: 504 Rating:
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https://support.automation.siemens.com/WW/llisapi.dll?query=6ES7326-2BF01-0AB0&func=cslib.cssearch&content=skm%2Fmain.asp%3Ftab%3D2&lang=en&siteid=csius&objaction=cssearch&searchinprim=_searchinprim_&nodeid=99&x=16&y=8 download the pdf and look @ page 145 E.Yup |
| 7/11/2009 2:53 PM | |
Joined: 10/7/2005 Last visit: 11/13/2024 Posts: 3027 Rating:
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Hello jonae I wonder if Siemens service & support has problems answering your question simply because they are struggling to understand it. The so called "Short circuit detection" can be a bit of a misnomer and there are two types of short circuit detection active in your card. One is the “short circuit” of a foreign 24V supply (or cards L+) with the F-DQ that drives the actuator (which is obviously really bad and must be detected as it would otherwise mean that the contactor stays ON even if the F-DQ is off). In order to be able to detect this foreign 24V intrusion, the F-DQ does a so called “Dark period” test during which it switches off the F-DQ (for <1ms) and monitors internally that there is no 24V present on the F-DQ (note that this dark test is disabled if you use the diode output for redundant modes). This also the reason that the manual (link at bottom) has table thatshows a relationship between permitted capacitance and load current. The other one is a “short circuit” (aka cross circuit) of the F-DQ straight to M. This (while detected by the card) is less of a problem since it means that you “rob’ you actuator of its 24V and it will inherently fail safe (switch off). Nonetheless, the manual has quite rightly a warning which says that: "To avoid cross circuits between P and M of a fail-safe digital output, you should connect the relay between P and M to protect against cross circuits (for example with cables separately sheathed or in a separate cable duct)." Anyway, I hope this helps somewhat (even though it doesn't really answer your specific question) and just in case you don’t have it yet, here is the link to the manual that has more useful info on the subject: ET200M F modules |
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