Volume 1, Issue 6

APPLICATION ARTICLE

Learn how one of our integrators utilized Entertron's products and philosophy to provide their customer with an off the shelf control solution that protects the customer's intellectual property. more >

If you have an application that you would like to submit for consideration, email us at plcs@entertron.com and in the subject area type in "application article"

TECH TIPS

In the world of analog, there are many sources of noise that can affect the reliability of analog signals. In order to eliminate and prevent noise on analog lines there are some basic rules to follow.

  1. When determining your analog requirements and devices, it is always best to use current type devices that can accept a 0-20 mA or 4-20mA signal whenever possible. In my experience current inputs devices seem to be less noise prone than voltage type analog.

  2. Use the shortest length of cable possible when connecting to the device. The longer the cable, the greater the possibility for noise being introduced into the system.

  3. Use shielded cable whenever possible to help reduce analog noise.

  4. Keep all analog lines away from inductive devices such as transformers, solenoids, and higher voltage power lines.

  5. Never run power lines and analog lines together in the same conduit.

  6. Whenever possible try to run the analog devices off of a separate power supply from the PLC and inductive devices. (Not always necessary but it is a good practice)

  7. Sometimes noise cannot be helped, in order to stabilize the analog register you can put a Sampling filter that will read the analog register on a less frequent basis in order to slow down the analog changes. Another way of reducing a noisy signal is to create a math routine to take a few samples and average them together.

If there are any questions you would like answered, email us at plcs@entertron.com and in the subject area type "tech tips question"

THE PROGRAMMERS CORNER

Sometimes when writing a ladder program, it is required to track or store some values for data logging , averaging or maybe even a non linear analog device that needs the math changed depending on where the analog signal is currently . Our Elite 2000 controller has some very nice commands for accomplishing tasks like these.

Indirect Put - This command is used for making the put command point to a variable register instead of giving it a set register to put values in. Indirect put looks at the register that it is referenced to and uses the value in that register as the actual register to put the value into.

Please see the example

Indirect Get - This command is used for making the get command point to a variable register instead of giving it a set register to get values from. Indirect get looks at the register that it is referenced to and uses the value in that register as the actual register to get the value from.

Please see the example

Eware32 Tips and tricks

When creating a ladder program or modifying an existing ladder program it is extremely important to document the program. When creating a new program it is always a good rule of thumb to describe what each rung is doing in the ladder program so that if you ever have to go back and troubleshoot the program or just add something to the program it will make it much easier to know what is happening in the program sequence, rather than having to trace all the contacts and coils and re-map out the program operation. When possible, it is also a good idea to provide names to your contacts and coils relating to their respective function. For example, if relay 25 is being used for a manual /auto selection then it would help to name the relay, so that everywhere in the program where relay 25 is used it also gives its label and makes the program easier to follow.

Eware32 has some features that help with program documentation. Under view in the file menu there are three selections to help with the documentation.

  1. Show Comments selection is used to show the comment areas above each rung. This is also how the comments get changed or put in. By double clicking in the comment area it will bring up the comment window to allow the text to be changed for the rungs comment.

  2. Show Labels selection is used to show/hide all contact and coil labels. Under the tools menu there is a selection for this is used to assign a label to an actual ladder item.

  3. Show Cross Reference selection is used to display a list of all the Inputs, Outputs, Internal Relays and Internal Registers (TC) and also shows what rungs they are each used on. This list makes it a lot easier to pick ladder items that have not been used or to quickly find what rungs a certain contact, coil or register has been used on.

If there are any questions you would like answered, email us at plcs@entertron.com and in the subject area type "programmer's corner question"

THE ENTERTRON ADVANTAGE

Does your application require various types of analog signals - Thermocouple, voltage, current, millivolt, plus or minus?

The traditional PLC world offers you very little in terms of flexibility. The "bricks" provide you with the basics - voltage or current. Usually the number is limited to 1 or 2. Some have expansion modules that provide more I/O, but you are still limited in terms of flexibility. You are very limited in terms of your options.

The "modular" PLCs, provide you with all sorts of analog options. Unfortunately, you usually have to buy more than you truly need. You may only need 1 RTD input, but with Allen Bradley's module for their Micrologix 1500, you get a total of six. This approach wastes your resources.

What can be done about this - why doesn't the manufacturer offer better flexibility to their customers?

The biggest obstacle to this way of thinking is the sheer size and volume that these Fortune 500 companies deal with. They are manufacturing thousands on pieces at one time, usually overseas and then shipping them to the USA. So, when the manufacturer is importing their own products, not to mention the many layers a customer must go through, it is nearly impossible to get what you truly need.

There are two options:

  1. Build your application around the components you have available.

  2. Find a manufacturer that is both willing and able to work with you.

Entertron offers extensive analog capabilities on two of its embedded programmable logic controllers (ePLCs):

  1. Smart-PAK PLUS

  2. Elite-2000

The Smart-PAK PLUS offers an analog only expansion card, to be used in conjunction with the main I/O card of 8 digital inputs / 6 relay outputs.

The analog expansion card for the Smart-PAK PLUS was designed with our OEM customers in mind. Providing as much flexibility as the 5" x 7" footprint would allow us. A total of 8 analog inputs and 4 analog outputs was what we could fit.

You are thinking that you can get a couple of analog modules for a DL06 and they are not that expensive. But, how many modules will you need for all of your different analog. You would require one module each for:

  • RTD inputs

  • Thermocouple inputs

  • Voltage inputs

  • Current inputs

  • Voltage outputs

  • Current outputs

The Smart-PAK PLUS analog expansion board can be configured for any of the above - ALL on ONE BOARD.

Can the other PLC manufacturers do millivolt inputs for load cells? Can other PLC manufacturers do wider voltage ranges (0-12 VDC or 0-30VDC analog inputs)? Chances are you will probably have to make concessions with the other manufacturers.

The Smart-PAK PLUS analog card can be manufactured for the following:

  • up to 4 type K thermocouples

  • up to 4 RTDs

  • up to 8 voltage inputs - 0-5, 0-10, +/-5, +/-10

  • up to 8 current inputs - 0-20 mA

  • up to 8 millivolt inputs

  • up to 8 custom voltages - contact factory to discuss your needs

  • up to 4 voltage outputs - 0-5, 0-10, +/-5

  • up to 2 current outputs - 0-20 mA

  • up to 4 custom voltages - contact factory to discuss your needs

The Elite-2000 analog card was designed in much the same way as the Smart-PAK PLUS - but with more. The Elite-2000 can have up to two analog cards with a maximum configuration of 8 inputs / 8 outputs per card. Unlike the Smart-PAK PLUS and other PLCs analog cards, the Elite-2000 analog card was designed with its own processor. All sampling is done on the analog card, providing updates to the main processor every scan of the ladder code. With other PLCs, more analog means a slower scan rate. Not with the Elite-2000. The Elite-2000 analog can be configured as follows:

  • up to 16 type K thermocouples (8/card)

  • up to 16 RTDs (8/card)

  • up to 16 voltage inputs - 0-5, 0-10, +/-5, +/-10 (8/card)

  • up to 16 current inputs - 0-20 mA (8/card)

  • up to 16 millivolt inputs (8/card)

  • up to 16 custom voltages - contact factory to discuss your needs (8/card)

  • up to 16 voltage outputs - 0-5, 0-10, +/-5 (8/card)

  • up to 6 current outputs - 0-20 mA (3/card)

  • up to 16 custom voltages - contact factory to discuss your needs (8/card)

Both the Smart-PAK PLUS and Elite-2000 are manufactured in the United States. We do not build a warehouse full of cards and tell you this is what we have and this is what you can order. To the contrary. Each analog card is build to order. Due to the endless possibilities, it would be impossible to keep even a small percentage of configurations in stock, because EVERY CUSTOMER'S requirements are different.

PRODUCT NEWS

Entertron now provides free downloads of all software and manuals for our products. Please visit our newly designed customer support and file archives page to download our information.

Please note that Eware32 and the software for our operator interfaces and touch screens is password protected. You will need to contact Entertron for a password to these downloads. The manuals are not password protected.

SPECIAL OFFERS

We continue with great success our OEM introductory offer. Any OEM that has never purchased from Entertron in the past can take advantage of this offer - 50% off any controller, in any configuration. For more information, click for details.

To the many students that are currently learning about the incredible world of PLCs and programming, we are offering you a special student discount - Any controller, any configuration - 20% off (includes computer cable and programming software). Compare this to other offers and you will see the benefits.

CLOSING NOTES

For those of you who are considering an "all in one" packaged PLC (both operator interface and PLC), here are a few things for you to consider, prior to purchasing:

  1. All wiring terminates to the door of your enclosure, unlike the separate PLC and operator interface products that have two connections: one for the serial port and one for the power cable. There will be a huge wiring harness going to the door of your panel.

  2. The output rating will be less than the traditional PLCs and far less than Entertron's controllers due to board size and component ratings constraints.

  3. Possible replacement will be challenging in that you will have to remove the entire controller / operator interface

  4. One processor for both the operator interface and PLC greatly reduces the scan rate of your application.

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