Moving Data In Siemens Ladder Logic

[Perpetual Suffering]

I'm having a heck of a time figuring out how to efficiently move the decimal value 1150 into MW20.

Can this be done using the MOVE command? Does the MOVE command support moving decimal values? Is it really that simple?

 

[cjd1965]

Try pressing F1 on the move block and read the helpfile.....

 

[L D[AR2P#0.0]]

TIA portal or "Classic" Step 7 ?

 

[Perpetual Suffering]

I am using TIA Portal.

I always try reading the help files first, but I have found them to be incomprehensible and useless 99% of the time.

 

[gclshortt]

http://www.automation.siemens.com/doconweb/pdf/SINUMERIK_SINAMICS_04_2010_E/S7P.pdf?p=1

Search in this PDF for 'Introduction to Data Types and Parameter Types'. Remember that the negative number is just a binary interpretation.

Regards,
Garry
http://www.accautomation.ca

 

[JesperMP]

Based on PS' previous posts it must be TIA.
Use the online help in TIA.

MOVE moves constants or variables into variables.
In TIA, MOVE does not require that the type of the variables involved match if "IEC check" is turned off. In TIA MOVE can move entire ARRAYs and STRUCTs. In this case the type and size must match. (In STEP7 Classic, MOVE does not check source and destination type at all).
MOVE moves the bitpattern. No conversion takes place between different types.
If MOVE moves a bitpattern into a smaller size destination than the source, the highest bits are lost.

 

[JesperMP]

Maybe PS' problem is that "IEC Check" is on, and MW20 default type is WORD. So trying to pass "1150" which is an INT wont be accepted.

 

[Perpetual Suffering]

Thanks for all the input guys. I've decided to just edit the word bit by bit. Maybe I can learn a smarter, more efficient way of doing it later on.

 

[daba]

Based on PS' previous posts it must be TIA.
Use the online help in TIA.

MOVE moves constants or variables into variables.
In TIA, MOVE does not require that the type of the variables involved match if "IEC check" is turned off. In TIA MOVE can move entire ARRAYs and STRUCTs. In this case the type and size must match. (In STEP7 Classic, MOVE does not check source and destination type at all).
MOVE moves the bitpattern. No conversion takes place between different types.
If MOVE moves a bitpattern into a smaller size destination than the source, the highest bits are lost.

Life is so much simpler in Allen-Bradley land...
A MOV instruction puts a copy of the source data into the destination, and automatically performs any data conversion that may be needed. No check boxes to forget, no configuration needed, it just does it....

Although to be fair, if Siemens is what you've got to work with, get used to reading the "help" files...

 

[Perpetual Suffering]

Life is so much simpler in Allen-Bradley land...
A MOV instruction puts a copy of the source data into the destination, and automatically performs any data conversion that may be needed. No check boxes to forget, no configuration needed, it just does it....

Although to be fair, if Siemens is what you've got to work with, get used to reading the "help" files...

I think I now better understand why Siemens has had such difficulty gaining market share in the US. Their product is robust and flexible, but often terribly counterintuitive and unfriendly.

Here's another dummy question. I have searched to the ends of the earth and cannot find where the scaling function in the Siemens HMI is. My co-workers tell me it does exist, but will not tell me precisely where it is located in the HMI programming interface (hazing the newbie of course). Google gets me nowhere, just like the Siemens support website.

Good grief Siemens support is just horrendously bad. If you don't have a co-worker to show you what you need to know you are really and truly on your own to somehow intuit your way through the pitch black fog, which often means literally guessing your way through some of the most arcane interfaces and terminology I have ever seen in my life.

Thus far, simply refusing to give up has been my only consistently effective survival strategy.

 

[Aabeck]

I downloaded & was going to print out the Step 7 Pro manual (as I have for RSLogix 500, 5000 & 5) but then noticed the file was 10,066 pages - just a few reams of paper!

Not something anyone was ever going to read completely.

 

[rQx]

I think I now better understand why Siemens has had such difficulty gaining market share in the US. Their product is robust and flexible, but often terribly counterintuitive and unfriendly.

Here's another dummy question. I have searched to the ends of the earth and cannot find where the scaling function in the Siemens HMI is. My co-workers tell me it does exist, but will not tell me precisely where it is located in the HMI programming interface (hazing the newbie of course). Google gets me nowhere, just like the Siemens support website.

Good grief Siemens support is just horrendously bad. If you don't have a co-worker to show you what you need to know you are really and truly on your own to somehow intuit your way through the pitch black fog, which often means literally guessing your way through some of the most arcane interfaces and terminology I have ever seen in my life.

Thus far, simply refusing to give up has been my only consistently effective survival strategy.

If my memory is correct you find the scaling in the tag table, in the properties of the tag.

And regardning your concerns I can say that for me that has learned to program PLCs using Siemens. I have the same problem you have but I have it with AB. TIA portal is like a ferrari for me while working with RSlogix is like learning how to ride a bike

 

[jstolaruk]

Having to switch constantly between the two platforms, I find both have strengths and weaknesses. I find a bigger gap when it some to using safety PLCs and components; the programming edge going to RA but Siemen's product line is more thorough. RA's weakness in safety is their drives - way behind.

Siemen's telephone support has gotten very good. I prefer RA when given a choice but Siemens no longer scares me like it did 10 years ago.

 

[Perpetual Suffering]

If my memory is correct you find the scaling in the tag table, in the properties of the tag.

And regardning your concerns I can say that for me that has learned to program PLCs using Siemens. I have the same problem you have but I have it with AB. TIA portal is like a ferrari for me while working with RSlogix is like learning how to ride a bike

In the properties of the tag! Aha! Many, many thanks for the tip.

 

[Perpetual Suffering]

I downloaded & was going to print out the Step 7 Pro manual (as I have for RSLogix 500, 5000 & 5) but then noticed the file was 10,066 pages - just a few reams of paper!

Not something anyone was ever going to read completely.

I've noticed this as well. I do understand and appreciate that the documentation is being written more or less by engineers for engineers but it would be helpful if they would also provide condensed, more practical guides for those of us just getting started. The 600, 1000, or 10,000 page manuals just aren't practical for somebody who needs answers in a reasonable amount of time.

Thanks again to the veterans here willing to share their knowledge and experience and tolerate rookies like me who are floundering around just trying to get a foothold in the industry. I guess if it was easy, everybody would be doing it, right?