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cannot force Analog Outputs (S7-315 using TIA)

Created by: garf123 at: 10/28/2011 1:50 AM (9 Replies)

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10/28/2011 1:50 AM	Rate (0)
garf123 Posts: 18 Rating: (0)	Hello Experts, I am using TIA V11 SP1patched with update 2. In my Force Table, I can force other Discrete Outputsjust fine, but not any of my Analog Outputs. My analog output module (AO8x12 bit, 6A613325HF000ab0) shows no configuration errors while online. Iamforcing the same addresses that the module automatically assigned itselfduring configuration. For example, AO channel 0 is using Q256, so in my Force Table I enter QW256:P which TIA changes to %QW256:P, and then I have tried forcing values in bothBCD anddecimal format. I have no other code inmy PLC and I don't want to add any to work around this issue....I just want to be able to ForcingI/O for now and check out my hardware. Anyone know why I cannot force these Analog Outputs?
garf123 Posts: 18 Rating: (0)
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10/28/2011 9:56 AM	Rate (0)
Marcjan Platinum Member Joined: 4/22/2010 Last visit: 12/13/2024 Posts: 5697 Rating: (715)	Hello, Read this topic: /tf/WW/en/Posts/62858 It's about step 7 v 5.x software but the solution might be the same because it's not a problem in the programming software, it's how the 300 series works. Regards, Marcjan
	Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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10/28/2011 4:33 PM	Rate (0)
garf123 Posts: 18 Rating: (0)	Thanks Marcjan, it's working now. For those readers of this post, I will summarize what I did and try totranslatethis into simple terms: Apparently to be able to Force analog outputs, you need to manually changea "memory size" property in the PLC offline, compile, and download. In the TIA software, right clickon the PLC and select properties and select the Cycle tab. In there you will find 2 fields called "Size of the process-image input area" and "Size of the process-image ouput area". In my PLC (S7-315-2 PN/DP), I changed these values from 128 to 500. I just randomly choose 500 not knowing what the implications are and not having time to dig through Siemens manuals to figure out why this PLC cannot just"self allocate" enough memory toForce module IO (a very common task)whenever a module is added to the PLC's configuration. In my opinion, it's a shame I have to manage this myself for such a simple task I wanted to do (Forcing IO). Anybody have an opinion about the 500 value I used (good/bad)? In my PLC rack, I only have the following modules in this order:8ptAO, 8ptAO, DM370 dummy module, 16ptDI, 8ptDO, 8ptDO.
garf123 Posts: 18 Rating: (0)
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This contribution was helpful to 1 thankful Users Marcjan

10/29/2011 6:03 AM	Rate (0)
umencho Diamond Member Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	The max. number there is 2048. What are the conditions for assigning the addresses of I/O modules (central or distributed) to an S7 CPU? http://support.automation.siemens.com/WW/view/en/12996906 (Chapter 6). Best regards, Hristo Mihalev

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10/31/2011 3:46 PM	Rate (0)
garf123 Posts: 18 Rating: (0)	Hello Hristo, Thanks for thelinks. In the TIA software, the I/O addresses were automatically selected by the softwarewhen I drag/droppedmy I/Omodules into the rack configuration from the picklist of availablemodules.Theyautomatically took these addresses:8ptAO at slot 4 (Q256-271), 8ptAO at slot 5(Q272-287), DM370 dummy module at slot 6(I288), 16ptDI at slot 7(I12-13), 8ptDO at slot 8(Q16), 8ptDO at slot 9(Q17). I like this auto address assignment feature in the TIA software. But it is toobad the TIA software cannot also at the same time automatically adjust the"size of the process-image input/ouput area"parameters when a module is dropped into the configuration. Adjust it to a minimum size that would allowpeople to be able to force the analog outputs like the discrete outputs could be. In my experience with other PLCs (Allen Bradley etc), their I/O iseasily "forceable"right afterthe modules are added to the configuration, and there is no need to manually adjust a "memory size"parameter deep down in the bowelsof the PLC beforehand. ForcingI/O is a very common task for hardware checkout, and so in my opinion it should be more easily accomodated.
garf123 Posts: 18 Rating: (0)	Last edited by: garf123 at: 11/17/2011 3:55 PM
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10/31/2011 6:00 PM	Rate (0)
umencho Diamond Member Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	Eee OK I am fully with you! Comparing with other brands of PLC might be the Siemens' issue with "force" is a 'differnet'. but according to me, this is not a problem if you know the right way to do it after. KEEP PLAYNING with Siemens! best regards, Hristo Mihalev

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11/14/2011 6:41 PM	Rate (0)
garf123 Posts: 18 Rating: (0)	I'll close my own thread by just saying that it was very difficult finding the answer on how to do force analog outputs. The previous post said something like "..it's not too bad once you know how to do it". That's true, but the main problem with Siemens PLCs (compared to AB for example)is that common tasks like thiswhich should be very simple/quick/intuitive are not!!! That's whySiemens PLCsare not very popular in my part of the world, and never will be.
garf123 Posts: 18 Rating: (0)
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11/14/2011 8:46 PM	Rate (0)
umencho Diamond Member Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	Fully agree with you, again! But only in your world (after "the big water"). But even there is not a true. Just my opinion. Best regards, Hristo Mihalev

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11/17/2011 3:46 PM	Rate (0)
garf123 Posts: 18 Rating: (0)	Sorry, I disagree. It's a very true statementthat it isNOT easy to force analog outputs as I described when I started this thread. You cannot build a PLC configuration (CPU/modules), go online, and force analog outputs on an analog output module unless you know first how to expand "a memory setting" in the CPUI mentioned in my post above. Nobody who posted showed any links to documentation that clearly explains this requirement, and no other PLCI knowofmakes itas difficult like Siemens does. I feel you are trying to hide this ugly fact aboutthis product. Enough said....I have myanswer to this thread I started and no longer need any additionalnon-technical comments disputing this and trying to put a positive spin on a poor design. See myunderlined text in a previous post in my thread for what would be a good design.
garf123 Posts: 18 Rating: (0)	Last edited by: garf123 at: 11/17/2011 6:03 PM Last edited by: garf123 at: 11/17/2011 3:56 PM
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7/13/2015 1:55 PM	Rate (0)
Min_Moderator Platinum Member Joined: 9/3/2014 Last visit: 3/13/2019 Posts: 4766 Rating: (122)	New question published by saurabh. bielo is split to a separate thread with the subject S7 300. change DO points. Best regards Min_Moderator

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