Many of the great questions in life begin with the word ‘where’. Where do we come from? Where are we going? Where should I install my LGH File Inspector?
While I cannot provide a whole lot of input on the first two questions, I do have some suggestions on where to install your LGH File Inspector.
In this Tech Support Corner blog post, we will explore some common factors that we have seen impact, or drive, the ideal placement of an LGH File Inspector installation – a question that we get quite commonly from users like you.
On the surface, the question of where to installed the LGH File Inspector seems quite simple to answer. Since the LGH File Inspector requires access to the LGH files generated by Windows, the logical place to install the software would be on the system where AVEVA InTouch (formerly Wonderware)is installed. And as basic logic general dictates – this is the simplest solution, so it is probably the right one.
Unfortunately, in many systems, it is not so easy. Many times InTouch is running on operator panels so that is where the LGH Files exist as well. And having to access software running on remote operator panels can be come problematic when it impacts the operator’s ability to see the HMI.
In other situations, we have seen integrators who need to access LGH Files for several disparate systems; access to the machine is no issue, but the software cannot run on the local InTouch node because the data must be accessible remotely.
So, given the above variables, the next question is what options do we have:
Depending on the situation, the simplest solution of just installing LGH File Inspector on the local InTouch machine can be less than ideal and may simply not be an option for every system. Direct access to the servers where AVEVA InTouch is installed (and the LGH file data exists) may be impossible and/or limited to maintenance/downtime windows.
While using a script or scheduled task to copy or move the LGH files to a network accessible location does provide some additional flexibility, it also adds an additional step. The major drawback here is that running scheduled file transfers allows access to the data only after it has been transferred.
If the file transfer only happens once a day, for instance, you would be limited to what data you actually have access to at any given time. And running the file transfers more than once a day may not be realistic based on the other demands on the system.
Our third option allows access to the remote file system directly, in similar fashion to a network drive. I am, of course, referring to using SymLinks (Symbolic Links).
If you are joining us from a Unix (*nix) world, you are probably very familiar with these guys, and you will be delighted to know that symbolic links are possible in the Windows world as well.
Symlinks – put simply – are similar to shortcuts, and provide references to files and directories located elsewhere (i.e. remote). Consider the following example:
My LGH File Inspector is installed on my local machine, with InTouch running on a remote host, (Hostname WWSP2014) specifically in the LGHDataFiles directory on the C:\ drive of that remote host. I can create a directory on my local desktop that will resolve to the C:\LGHDataFiles on the remote host and can access those files then as if they were present on my local machine.
The following command prompt operation will do the trick:
mklink /D C:\users\mholbach\desktop\LGHFiles \\wwsp2014\C$\LGHDataFiles
Once executed and successful, we see the following:
Seems pretty simple right? Let’s break that command down piece by piece so you can easily apply it to your own systems:
In the LGH File Inspector, I can now simply add this SymLink directory as an LGH File Data Source normally and any files read from this directory will come from the remote machine.
Now this does have several considerations that should not be overlooked:
Simply adhere to the above considerations and you'll have a relatively easy method for accessing remote LGH file data in the same fashion that you'd access local LGH files using the LGH File Inspector.
If you've ever needed an easy-to-use, flexible solution for accessing remote historical process data that is stored in LGH history files, I encourage you to click below to get started with your own remote LGH files using the free trial of LGH File Inspector.