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Old December 9th, 2014, 03:04 PM   #1
lbeh
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How to switch drivers

I am attempting to take an old program and use a new driver for it. Each time I try Who'sActive or System comms... and get the program to download and work with the new driver, I lose the comments and some of the data files.

I am using the free version of RSLogix 500 (Micro Starter Lite I believe) and a Micrologix 1100 PLC.

Can someone help me to understand what is going on, or how to correctly switch the driver?

Thanks in advance.

Last edited by lbeh; December 9th, 2014 at 03:32 PM. Reason: list the software and PLC information
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Old December 9th, 2014, 04:04 PM   #2
realolman
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I don't think I know for sure what you're saying here, but I don't believe the comments download and upload with that kind of processor.

I think you have to have the comments in a file in the computer

I'm not sure that the driver has anything to do with it

could be wrong... often am
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Old December 9th, 2014, 04:11 PM   #3
Ken Roach
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Are you certain you are downloading, and not uploading ?

When you do the "Who Active Go Online" with RSLogix 500, the software checks the program in the controller to see if it matches the program you have open.

If it does not, it checks on your hard drive for programs with the same name and the same checksum. I'm not sure if it looks in the default directory, or in the last directory you had open, or in several other places.

The problem comes when you have an uploaded, without-comments version of the program that's currently in the PLC on your hard drive. Unless you very carefully make sure you are downloading a new program instead of "going online", you'll end up with RSLogix 500 pointed to the offline copy of the program it thinks matches most closely the program in the PLC.

This isn't based on specific knowledge of the under-the-hood operation, just my experience going "wait, no, that's not the right program !".
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Old December 9th, 2014, 05:04 PM   #4
lbeh
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Is there a good way to switch drivers then?
Say I have a program that was set up with an ethernet driver. Now I want the same functionality (and comments) of the program just with a new driver (in my case a DF1/RS232).

Is it best to just create a new file with the new driver specified and copy everything over?
Or just delete any old versions of the program off the computer?

Thanks again for the comments.

Last edited by lbeh; December 9th, 2014 at 05:24 PM.
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Old December 9th, 2014, 05:45 PM   #5
shawn_75
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For that processor, you can configure channel 0 to your desired DF1 setup and also configure channel 1 to your desired ethernet setup. No need for saving different versions on your PC. Just download the program to your 1100 with both channels configured. In RSLinx, browse with the driver appropriate for how the 1100 is connected to your PC.
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Old December 11th, 2014, 08:30 AM   #6
gbeaker
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If I understand correctly, you just want to communicate to the PLC using a different protocol than the default for that program.

Just open the existing file and goto the Tools menu, then Options. Then select the Communications Tab. Under "Current Settings" change it to the driver you want to use. Now save the file. Any time you open it, it will default to that driver when trying to communicate.

Quote:
Originally Posted by lbeh View Post
Is there a good way to switch drivers then?
Say I have a program that was set up with an ethernet driver. Now I want the same functionality (and comments) of the program just with a new driver (in my case a DF1/RS232).

Is it best to just create a new file with the new driver specified and copy everything over?
Or just delete any old versions of the program off the computer?

Thanks again for the comments.
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Old December 11th, 2014, 03:10 PM   #7
Geospark
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RSLogix 500 - Driver Communications Path

Quote:
Originally Posted by gbeaker
If I understand correctly, you just want to communicate to the PLC using a different protocol than the default for that program.

Just open the existing file and goto the Tools menu, then Options. Then select the Communications Tab. Under "Current Settings" change it to the driver you want to use. Now save the file. Any time you open it, it will default to that driver when trying to communicate.
Yes gbeaker, that's how I am reading it too, but there are a couple of ways to skin this cat, and maybe "slightly" easier too?

Quote:
Originally Posted by lbeh
I am attempting to take an old program and use a new driver for it. Each time I try Who'sActive or System comms... and get the program to download and work with the new driver, I lose the comments and some of the data files...

...Can someone help me to understand what is going on, or how to correctly switch the driver?...

...Is there a good way to switch drivers then?
Say I have a program that was set up with an ethernet driver. Now I want the same functionality (and comments) of the program just with a new driver (in my case a DF1/RS232).

Is it best to just create a new file with the new driver specified and copy everything over?
Or just delete any old versions of the program off the computer?
lbeh,

So you appear to be talking about changing the driver path for the program in RSLogix 500?

Your "old program", or existing program, has its driver path set to communicate with the controller using the Ethernet driver while connected to Channel 1?

You now want to permanently change the program's driver path to use the DF1 driver while connected to Channel 0?

Or...

You want to have two separate copies of the program, one set to the Ethernet driver path, and the other set to the DF1 driver path?

"Path" being the operative word here.

In RSLinx Classic, you should have both the Ethernet and DF1 drivers properly configured. You can have the serial cable and the Ethernet cable connected between the controller and your computer at the same time to test both drivers. If you can successfully see the controller in RSLinx, when using either driver to browse to it, then that verifies you have good comms to both channels on the controllers. You can now close or leave RSLinx Classic.

Next...

In RSLogix 500, the offline program's current driver communications path is the path that was last saved for this program to communicate with the controller. This is displayed as "Driver:" and "Node:" in the top left area. This is the driver path that the program will attempt to use when you select Go Online, or Upload/Download.

To permanently change the driver path for the program, go to...

Comms>System Comms.
Browse to the controller using which ever driver you require, and then highlight the controller.
Then, tick "Apply to Project" in the bottom right corner.
Do not use Online, or Upload/Download.
Click "OK" and then Save the program (click floppy disk icon).
This new driver path is now permanently saved for this program. Every time you open it, it will attempt to use this path to connect with the controller, when ever you use Online, or Upload/Download.

To create two identical programs, but use one of the two driver paths in each...

Change the driver path under System Comms, as per above, only this time do a Save As, and save the program under a different name, such as "MY_PROGRAM_DF1", or "MY_PROGRAM_ETH". This will save a copy of the program under the new name, while leaving the original program file intact. Now when you want to connect, open the program for the driver you want.

The above "does what you asked", I think, but you don't necessarily have to do that to use different driver paths. You should be able to have one driver path set as permanent, and just use the less frequently used path on-the-fly.

For instance, you might normally connect to the controller on Channel 1 Ethernet from a network point in your office. The driver path for this connection is permanently saved in the program. Today you are working local to the controller and want to temporarily connect to it using the DF1 driver, which is already configured and working in RSLinx Classic. So the serial cable is connected to the controller's Channel 0.

When you open the program you will see the permanent path is set for the Ethernet driver. You would not select Go Online, Upload, Download, as they would all attempt to use the permanent Ethernet driver path. To temporarily use the DF1 driver path, you would use Who Active Go Online. Then browse to the controller under the DF1 driver, and click OK. The program should then go online using this temporary path. You will notice that the driver path in RSLogix 500 has changed to the DF1 driver path, but this is just temporary, and only to inform you of which driver path you are currently using.

When you Go Offline again, you'll notice the displayed path will revert to the permanent path, as it was untouched. You can then close your program, safe in the knowledge that the next time you open it back in the office, you can simply choose Go Online, Upload, or Download and it will use the correct Ethernet driver path once again.

You can also view the current driver path setup under Controller Properties>Controller Communications" tab. Here you can also see a history of recent paths that have been used. You can also access Who Active from here.

Similarly, and as mentioned by gbeaker, you can navigate to Tools>Options>System Communications tab. Here you can view the same info as under the Controller Communications tab, with the addition of access to the Upload, Download and Online features.

The System Comms>Apply to Project option is the quickest method for permanently changing the program's driver communications path.

Regards,
George
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Old December 11th, 2014, 03:11 PM   #8
Geospark
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RSLogix 500 - Checksum Correlation - Under the Hood...

Quote:
Originally Posted by Ken Roach
...When you do the "Who Active Go Online" with RSLogix 500, the software checks the program in the controller to see if it matches the program you have open.

If it does not, it checks on your hard drive for programs with the same name and the same checksum. I'm not sure if it looks in the default directory, or in the last directory you had open, or in several other places.

The problem comes when you have an uploaded, without-comments version of the program that's currently in the PLC on your hard drive. Unless you very carefully make sure you are downloading a new program instead of "going online", you'll end up with RSLogix 500 pointed to the offline copy of the program it thinks matches most closely the program in the PLC.

This isn't based on specific knowledge of the under-the-hood operation, just my experience going "wait, no, that's not the right program !".
Ken,

We've all been there!

What is actually compared to what before going Online can be a little bit deceiving, or tricky. I'm sure many a user has scratched their heads thinking what on earth is going on here when they try to Go Online? I just had it open? I just came Offline? I was Online a few minutes ago? Why is it not the right file any more? Why is it suddenly looking for some "other" file to be used?

The following hopefully offers a little more insight into this sometimes perplexing task...

Checksum & Co. - under the hood...

When a new program is created in RSLogix 500, it has no checksum, or to be more specific, it has a checksum of "0". The first Verify Project of the program will generate a unique checksum for the Offline Image of that program. The Offline Image checksum reflects the contents of the Offline program's Database. If an Offline Edit is carried out, say adding a rung of logic, or adding a Data File, then the Offline Image checksum is again temporarily set to "0". The next Verify Project will again generate a new checksum value for the Offline Image because of the modified contents of the program's Database.

So, the Offline Image has its own checksum.

The first time a new program is loaded into a controller, and goes Online, an Online Image is automatically saved to the program file in RSLogix 500. This Online Image is thus retained within the Offline copy of the program i.e. within the *.RSS file. This Online Image reflects the contents of the controller's Database.

The Online Image also has its own checksum.

Why?

This is because Online Edits are automatically saved to the Online Image in the *.RSS file, as they are performed i.e. you do not have to explicitly save the program to update the Online Image. If after performing Online Edits, you do not save them to the Offline program, then the checksums for the Online Image and the Offline Image, within the same *.RSS file, will differ.

Say what?

So, even though you have opened a program, gone Online, performed Online Edits, not saved, gone Offline, and closed the Offline program, the *.RSS file's Online Image has changed. This is why it prompts you to save as you go Offline, as the two images are now different in the *.RSS file. If you choose to not save, the two images remain different. When you attempt to go back Online, you will get the No Matching File Found prompt.

So, we now know that there is an Offline Image, and an Online Image, within the same *.RSS file, and both have their own checksums.

So how do you synchronize them again?

By doing a save while Online, usually as you are editing, by performing an Upload to a selected file and saving, or by performing a Download.

Another item, included in the the Online Image, is the Processor Name as stored in the controller.

Why is the Processor Name needed in the Online Image in the *.RSS file?

If you open RSLogix 500, but do not open a program, and then attempt a Who Active Go Online, RSLogix 500 will first read the Processor Name from the live controller under the driver path you are attempting to Go Online with. It will then look to a default project folder, if one is set, to try to find a suitable *.RSS file to go online with. The default folder can be set under Tools>Options>System Preferences>Project Files Search Path.

If a folder is set, and their are *.RSS files present, then it will automatically look to the first *.RSS file alphabetically, and read the Processor Name stored in the Online Image within the *.RSS file. This is a rough pre-check as it only tries to match the first 8 characters of the Processor Name. If satisfied with the Processor Name, it moves on to trying to match the checksum between the Offline Image, and the Online Image, within the *.RSS file.

To be clear, the only check carried out between the live controller and RSLogix 500, before going Online, is the 8 character pre-check of the Processor Name. The checksum correlation is entirely done Offline within the chosen *.RSS file.

Why Offline?
Why is the Online Image in an Offline file to be trusted?

Because the Online Image in an *.RSS file, that was the last file used while Online to the controller, should always represent the latest Database in the controller.

Ok, but what if I copy that up-to-date *.RSS file, saving it under a different name, or even in a different location, and then perform Online Edits again with the original file and save?

Would this not create a scenario where both files have the same Processor Name and both have a matching Offline Image and Online Image, but only one of them has an up-to-date Online Image, correct for the controller's current Database?

Surely an attempt to Go Online with the copied *.RSS file, that did not perform the last Online Edits would correlate and attempt to Go Online, because the Processor Names matched, and the Offline Image and Online Image also matched?

i.e. If the checksum correlation is always carried out in the Offline *.RSS file, then how does RSLogix 500 prevent the above from happening?

Another under-the-hood check is performed...

When you save a program, another piece of data saved to the images is the *.RSS path/filename.

If you are Offline and save, only the Offline Image is written to.
If you are Online and save, both the Offline Image and the Online Image are written to, synchronizing them.

If you have an *.RSS file that has it's path/filename synchronized for both images, and then you save as another name, or even the same name in a different location, only the Offline Image is written to in the new *.RSS file, leaving the two images now unsynchronized.

If you attempt to Go Online with the copied file - Even though the Processor Name, Offline Image and Online Image all pass the first two correlations, this file will fail the third check. To resynchronize this file's images, for path/filename, you must perform an Upload Use File and then save.

So now, and as per above, the original file can Go Online as everything checks out, but now the copied file can also Go Online, even though both files have either different names, and/or locations.

As I write this, I have two programs open and Online to the same MicroLogix 1400 controller. They are identical except they have different path/filenames.

Ok, just to complete this picture...

If you open RSLogix 500, and you do have an open a program, and then attempt to Go Online, RSLogix 500 will first read the Processor Name from the live controller under the driver path you are attempting to Go Online with. It then checks if it roughly matches the Processor Name in the Online Image in the open *.RSS file. If this passes, it then checks the path/filename and checksum both match for the Offline Image and Online Image in the *.RSS file. If they both correlate, it will then Go Online.

If you open RSLogix 500, and do not open a project, and then attempt a Who Active Go Online, while there is no default folder set, or there is no existing file available anywhere that matches, then you must perform a Create New File. This is where you will end up Online with a controller with no documentation displayed.

The checksum is viewable under Controller Properties.

So what can change the checksum?
_Changing the processor name.
_Creating/deleting/modifying program files.
_Creating/deleting/modifying data files.

And what will not change the checksum?
_Modifying data table values.
_Editing documentation.
_Forcing, histogram, trends, etc.

Lesson for the day...

The controller does not care about anything to do with checksums, or filenames and paths, it only needs to see a matching first 8 characters for the Processor Name in the *.RSS file's Online Image. After that, it's all down to the correlation of the images within the *.RSS file.

Clear as mud?

Regards,
George
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