by Nugroho Budi from controlmanuals.com

The MVI46-MCM is a Modbus communication module provided by ProSoft Technology. The module can be installed in a SLC500 rack so it can communicate to other Modbus devices.

In Siemens PLCs the Status Word is an internal CPU register used to keep track of the state of the instructions as they are being processed.  In order to use STL more effectively it is important to understand the Status Word and its functions.

by Automation Training

The following is provided by Automation Training from their excellent Siemens Step 7 training manual. This is a really nice explanation of a difficult but important subject. Check out their website for hands-on and online training classes.

One of my most common questions is, “Where can I get a free download of RSLogix 500?”  For any serious development with SLC500 or MicroLogix there is no free option but there is a nice free option if you only want to learn and/or program a MicroLogix 1000 or 1100.  Programming a MicroLogix is very very similar to programming a SLC500 or in that case a PLC5 too. 

Allen Bradley offers as a free download a software package called RSLogix Micro Starter Lite which is essentially the same programming environment as RSLogix 500.  On top of that, they also offer RSLogix Emulate for free so that you don’t even need a PLC to run and test your ladder logic.  Keep reading and I’ll show you how to get the software and set it up.

by John Schop

One of the most powerful newer features of the RSLogix 5000 program is the ability to create Add-On Instructions. This allows a programmer to define an instruction that contains a commonly used function or algorithm (as a set of instructions), and use it as one instruction.

To illustrate how this works, I am going to create an instruction that operates a cylinder, and because I’m making an add-on instruction, I can use that same instruction to control any number of cylinders in my application

by John Schop

Have you ever lost data in a CLX processor, because you downloaded new code? Unfortunately, when you donwload a program to a ControlLogix processor, you also download the values of the tags (variables).

A solution to this problem that could be useful, is an Excel sheet that reads and writes values to the ControlLogix processor using the DDE/OPC capabilities of RSLinx.

In this article, I will show you how to create one of these sheets for your projects.

Here’s what you’ll need:

These are general guidelines for connecting, downloading and uploading from an S7-300 or S7-400 PLC. The following procedures were created using Siemens SIMATIC STEP 7 version 5.4 software.

by John Schop

For years now, Object Oriented Programming paradigm (or OOP) has been a commonly used programming practice, and has of course found its way into industrial automation as well.

by John Schop

I often find that using SFC's or Grafcets is the easiest way to design industrial automation systems. I have worked for several machine builders, and one of them had given the term 'SFC logic' another meaning. There was absolutely no process in their PLC logic that was not documented by an SFC or as I like to call it, a Grafcet. After some getting used to that, I absolutely loved the way it enabled me to program and troubleshoot complex machinery, and ever since, I've tried to use this method whenever I could.

Courtesy of: Inductive Automation

Water and Waste Water Plants Transform Using Web-Launched, Java-Based SCADA Software

Professionals in the water and waste water management field face a series of difficult challenges as they seek to stabilize and expand their service delivery capabilities, while at the same time meeting the regulatory reporting requirements of the state. As if that were not enough, they must accomplish this in the current economic environment facing local governments. Managers clearly need better ways of doing business and an economic model which will give them the functionality and scalability required at a price point that does not break the budget.