5/7/2008 3:37 PM | |
Joined: 9/27/2006 Last visit: 9/22/2024 Posts: 12282 Rating: (2684) |
Hello Jesper; I have saved this Siemens FAQ (entry ID:23451499) for whenever I have to clarify these issues in my own mind. It states that a Source Input (24 V) is a PNP transistor circuit; it especially states that your module is the one exception to the rule that all ET 200SDCinputs are sinking. Hope this helps, Daniel Chartier |
7/11/2009 3:50 PM | |
Joined: 10/7/2005 Last visit: 9/22/2024 Posts: 3021 Rating: (1054) |
Hello Simaticmanager Daniel (as usual) really did say it all, nonetheless I wonder if you have a typing mistakes in your your post which causes the confusion and/or it is because you overlooked the reference potential. The correct voltage ranges for logic 0 and 1 are (as per manual): For sinal "1": -15V to -30V, reference potential is L+ For sinal "0": +30V to -5V, reference potential is L+ Please note the reference potential of L+ in the specification. What this means is the following: Digital input switch is CLOSED (signal "1"): You will (typically) measure some -24V at the cards input (which is nowconnected to 0V common) with reference to L+ (which is typically +24V). In other words, you would measure 0V if you use0V common as the reference potential. Digital input switch is OPEN(signal "0"): You will (typically) measure 0V at the cards input (which is nowno longer connected to anything) with reference to L+ (which is typically +24V). In other words, you would measure +24V if you use0V common as the reference potential. I hope this clarifies things. |
Cheers |
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