PLCMentor.com

You might check this out: This looks like it's a lab guide.  He also has a PDF text on PLC's.  Most PLC books I have seen try to go about it with generic knowledge (ie, not a specific PLC type).  You then end up with generic knowledge that is useless.  Well, unless you just want to kinda understand what a PLC is.  I feel like you need to pick a manufacturer and learn on that platform.  Then you will actually have some practical knowledge.  

That's exactly the thought had when first reading the post.  I don't know if historian has the capability to write to the PLC as it is generally designed to just poll for information. Noorloai, can you go back to your Wonderware tech support and see if historian has the capability to write to the PLC and perform some simple logic.  The aim would be to create an on/off hearbeat at a set interval (ie, 1 sec on and 1 sec off).  If you can achieve that then you can analyze that bit in your PLC by using timers.  If the bit from the Historian stays on past one second or off past one second then the communication is considered lost and you can act upon that however you want in the PLC.

Evan - we have about 9 hours of wonderware training on our site that may be useful.  It was done in version 10, but most of the information still applies to later versions. 

There is also a 7 day grace period when you install the software.  If this is a quick look and done, you can probably just use that if you have access to the software installation files.

I would be interested in hearing a bit more on this when you swap some things around.  The class 3 msg has to do with HMIs, SCADA and other unscheduled communications including uploads/downloads.  It may be that swapping things around as pturmel mentions will clear things up.  One thing I saw with a quick google was people saying that firmware versions < 32 seemed to have issues with locking up class 3 comms.  I don't have any direct experience with this so just passing on what I've read.  Either way please update this thread when you have moved things around a bit. 

I do this with pretty much every project I put together.  I have a simulation mode that my system can go into that runs the routing that sets all of my i/o to inhibit.  It also enables the JSR that runs the logic to simulate inputs, puts my scaling blocks into a simulation mode, etc.  Its really great for batching systems as you can make sure everything works well as the system sequences through the batching steps.

Kollmorgen has an Ethernet I/P version of their drives that is fairly easy to connect to and their support is good.  Unfortunately you will probably have the same supply problems with their equipment as you are having right now. 

Ok now that everyone gets how it works the original question was why would you use it. Generally I have used this instruction to sort out information from communication with a non AB device or a blob of data from some other device.  For instance if you have a DINT where not all of the bits are pertinent poop, you may mask out the unnecessary stuff to make it easy to do comparisons.  I use this in conjunction with some GSV statements that store certain data in 4 bit lumps.  I can mask out everything else and then do simple comparisons with the result.  I actually think I got this right out of the book for checking comm status on system modules.  Granted, in retrospect, I could have just done the comparisons using bits...  But mine goes to 11  (maybe someone will get that reference).

I'll put another vote for the RedLion HMI's. Simple to use and will connect to about anything.  I will say that they are hard to come by now with all of the Covid delays going on.

As Joe mentioned DH+ is pretty resilient to abuse.  If you are removing the last PLC in the line, you can still just unplug the PLC and leave the connector, term resistor and all until you can properly modify things.  Once you dont have to worry about things going down, you can remove the cable from the preceding device and place the termination resistor at that location.   Just as a side note, DH+ actually had a more complex installation method of station connectors and drops off of the trunk line and a very specific cable that needed to be used.  In actual practice people found that it was easily daisy chained without any problems to service.  Not having the right cable can be a problem in certain instances and not having the proper termination resistors can cause issues also, but usually people can do lots of stupid stuff and still have an operating network. 

It seems that copying an empty string solves the problem and is simple.  Is there a problem with that method that would require any of the other methods discussed here?

Gotta agree with the learning ladder.  That said, program to your audience.  If you have a staff of computer science experts then maybe structured text is the way to go.  Generally with PLC's you are going to be working with a maintenance staff with electrical knowledge and those guys are who ladder logic was developed to make things easier for.  As Bob said, you can do a lot of advanced programming with PLC's now days.  It's generally better to program things as simple as possible in order to make things easier for those with less programming capability than you have.  Also, at 2AM my brain doesn't operate well enough to remember what all that indirect addressing was doing!  So in reality you are programming simple for your brain at stupid hours when it needs things easy too.  In PLC's often simple, repetitive, well organized with good documentation is better than optimized and compact. 

Looks like the software is in the Downloads/Demo software area.  I tried to copy the link: https://forums.mrplc.com/index.php?/files/file/868-rslogix-500-micro-starter-lite/

I'm not sure whether F10 still applies or if that was older software.  The steps prior to that - Monitor S:6 to determine the fault - will require getting online with the software.   RSLinx is the communications interface, but you will need RSLogix500 in order to get online and view the program and check that status word.  RSLogix500 talks to RSLinx which talks to the PLC.  For the Micro 1000 there used to be a freebie package available.  It used to be posted on this forum.

When you said they could download the program with RS500, does that mean they could open it in offline mode?  What messages did they get?  I would think if they could download it with the software they could edit it also.  I think there is some missing info here.