Controlling Your World One Contact At A Time  

AB to AD - DirectSOFT

This is the programming package for the AutomationDirect PLCs. It is produced by the fine folks at HOST Engineering and available from AutomationDirect.

For practice, a 100 step limited version of the software package is available for free online at AutomationDirect. The 'QuickStart' manual is available here. The full version of the manual is in PDF form in the 'Help' folder installed even with the demo version.

The full package license allows for non-simultaneous use installation on a desktop as well as a laptop. There is no cumbersome activation scheme. The pricing make the package very reasonable. There is no yearly support fee. When a major upgrade is available (supporting new CPUs) it can be purchased if you wish. Minor upgrades and bug fixes are always available for free online.

The files produced by this package are similar to that made by the older AB APS software. There are a number of files with the same project base name and different extensions. I find it easiest to establish a separate folder for each project.

The software – again similar to the APS package, contains all communication capabilities. On startup the package will scan for previously used communication links to see if they are still active.

There is no separate package like RSLinx. Indeed, if RSLinx is installed make sure that it is not running since, if configured, it will tie up a serial port even if the RSLogix software is not running.

Any tools which can be used to set up other modules (counter, communication etc) within the system will be available for selection once the DirectSOFT package is started. These other tools could also be invoked separately.

The package behaves as you would expect – allowing ladder creation, saving, downloading and monitoring. Cables for communication a very reasonably priced. Like the AB SLC and MicroLogix line, comments are not transferred to the CPU. About the only feature you may miss from RSLogix is drag-and-drop movement of information.

The program may be viewed in three modes – ladder, stage and mnemonic. It can only be edited in the ladder view though. The stage view attempts to show the stage relationship within a program (though I find this of limited usefulness). The mnemonic view shows the final mnemonic structure as will be transferred to the CPU.

Many of the instructions can be entered using its name. The only problem is the OUT instruction mnemonic. It is used for turning on a bit (similar to the OTE) and for transferring the accumulator to a single word destination. Once the letters 'O' 'U' and 'T' are typed followed by an Enter the OUT (bit) instruction shows. This can be changed to the OUT (word) form by pressing the slash (/) character. In fact the slash can also be used to toggle between Normally Open and Normally Closed versions of a contact and between the various forms of the inline numeric comparisons.

Like in RSLogix the ladder editing window can be split into two to observe different sections. Merely click on the small line at the top of the vertical scroll bar at the right side of the window and drag downward. (In RSLogix the small bar extends completely across the top of the window.)

Very flexible Data View windows can be created to observe the values of widely separated locations. While online these values are updated automatically and can be modified. Forcing of inputs and outputs can be done in the same window. Note that forced items become unforced after a power cycle. The window setups can be saved with very descriptive names.

Program / Project (Added 5/24/07)

In RSLogix, to edit a program which doesn't have online capability, you have to upload the program from the running PLC, even if you have the correct source, since you know that on downloading you will be overwriting the data tables. If you didn't upload first you would be writing old data.

In AD there is a distinction made between the ladder logic itself, which is called the 'program', and all the data tables. When the logic and the tables are considered together they are called the 'project'. So you have the option to upload and/or download just the ladder logic (the 'program') or the ladder with all the data tables (the 'project'). When online the buttons presented read and write just the 'program' (logic). You have to go to File-Save Project-To PLC (or To Disk) to deal with the entire set of the logic plus the data tables.

Being able to download just the logic ('program') means you could edit the logic far away from the machine without ever uploading and download it to the PLC without disturbing the process. It also means that a logic change to a number of nominally identical machines (differing only in their data tables) can be made once and downloaded to all the machines. But you have to take the responsibility of remembering the distinction in download/upload choices and use the correct one. For every benefit there is a price.

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Copyright © 2005, 2006, 2007 Bernard Carlton