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Mode selection

Created by: somlioy at: 5/31/2012 9:59 PM (4 Replies)

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5/31/2012 9:59 PM	Rate (0)
somlioy Posts: 9 Rating: (1)	Hi I have problems figuring out how to solve my problem in a proper way; I have a series of Digital outputs on my plc which I want to turn on in different combinations depending on a selection switch (4 modes). Lets say in mode 1, I want Q0.0, Q0.2 and Q0.4 to be turned on. In mode 2 I want Q0.1, Q0.3, Q0.5 to be turned on and so on. I hope someone got a good answer for how to solve this in a proper way.
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5/31/2012 10:14 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 2/7/2025 Posts: 15619 Rating: (2471)	somlioy Hi I have problems figuring out how to solve my problem in a proper way; I have a series of Digital outputs on my plc which I want to turn on in different combinations depending on a selection switch (4 modes). Lets say in mode 1, I want Q0.0, Q0.2 and Q0.4 to be turned on. In mode 2 I want Q0.1, Q0.3, Q0.5 to be turned on and so on. I hope someone got a good answer for how to solve this in a proper way. The problem must be more complicated than you describe. As given, it looks like the attached image which is relatively trivial. Attachment sample_logic.jpg (356 Downloads)
	science guy
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5/31/2012 10:37 PM	Rate (0)
somlioy Posts: 9 Rating: (1)	Yes I forgot to mention that some outputs will be used several times. Check attachment. It dosent seem to like that. When I'm enabling mode 1, I can see the blocks are glowing green in my program with monitoring on, but not in S7-PLCSIM. Only the last mode (network) works properly. Dose it have something to do with outputs beeing used again are turned off further down if I enable modes further up in my program? Attachment Uten navn.jpg (415 Downloads)
somlioy Posts: 9 Rating: (1)	Last edited by: somlioy at: 5/31/2012 10:41 PM Last edited by: somlioy at: 5/31/2012 10:39 PM
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6/1/2012 9:16 AM

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Ganes10

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somlioy
Yes I forgot to mention that some outputs will be used several times. Check attachment.

It dosent seem to like that. When I'm enabling mode 1, I can see the blocks are glowing green in my program with monitoring on, but not in S7-PLCSIM. Only the last mode (network) works properly.

Dose it have something to do with outputs beeing used again are turned off further down if I enable modes further up in my program?

Hello somlioy,
The physical outputs are written at the start of every cycle.

Look at this

In STARTUP and RUN modes, the CPU performs the tasks shown in the following figure.

STARTUP		RUN
A	Clears the I (image) memory area	①	Writes Q memory to the physical outputs
B	Initializes the outputs with either the last value or the substitute value	②	Copies the state of the physical inputs to I memory
C	Executes the startup OBs	③	Executes the program cycle OBs
D	Copies the state of the physical inputs to I memory	④	Performs self-test diagnostics
E	Stores any interrupt events into the queue to be processed after entering RUN mode	⑤	Processes interrupts and communications during any part of the scan cycle
F	Enables the writing of Q memory to the physical outputs

So the logic should be written in such a way that the output doesn't get overwritten.

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6/2/2012 12:02 AM	Rate (0)
somlioy Posts: 9 Rating: (1)	Probably easiest to just use SET block instead then and use a negative trig edge block on the mode-selector and just reset all outputs?
somlioy Posts: 9 Rating: (1)
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Mode selection

Created by: somlioy at: 5/31/2012 9:59 PM (4 Replies)

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Last edited by: somlioy at: 5/31/2012 10:41 PM

Last edited by: somlioy at: 5/31/2012 10:39 PM

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