Opto 22

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Local & outside the USA:(951) 695-3000
Toll-Free within the USA:(800) 321-6786
Fax: (951) 695-3095
Email: sales@opto22.com

Using Analog I/O with Variable Frequency Drives

SNAP analog I/O modules

A recent OptoForums post asked about using Opto 22 products to control a variable frequency drive (VFD). Among the responses is a link to our technical note on using VFDs with analog I/O.

VFDs attach to an AC motor to control the motor's output speed and torque. The VFD adjusts the motor's output to match requirements instead of keeping it continuously running at full power.

Because VFDs save electrical energy, using them saves you money on your utility bill. In addition, many utility companies offer rebates if customers add them to their motors.

Opto 22 analog SNAP I/O modules are great for controlling VFDs based on a condition, a process, a PID loop, or whatever you need. For more, see the technical note, "Using Opto 22 Analog Modules with Variable Frequency Drives" (form 1994).

N-TRON Products No Longer Available from Opto 22

N-TRON Ethernet networking products

Due to organizational changes at N-TRON, Opto 22 will no longer be able to resell their networking products, effective immediately.

A limited number of N-TRON products are still in stock, so order now from your local distributor or from Opto 22.

We still recommend N-TRON products for your Ethernet network. These tough devices work great with Opto 22 systems and are an excellent choice in an industrial setting.

After current stock is gone, you can purchase networking products from N-TRON's distributors.

Please contact Pre-Sales Engineering with any questions or concerns.

Tech Tip: Use Your Brain to Avoid Disaster

Tank farm

OK, maybe that's a little strong...

But seriously, say you have a tank that is periodically refilled. What if the command to open the refill valve is received, but 15 minutes later when the valve is supposed to close, a communication problem prevents the I/O from receiving the Turn Off command?

SNAP PAC brain provides distributed control

One way to avoid potential problems like these is to use your brain—your Opto 22 SNAP PAC brain.

SNAP PAC brains provide distributed control for your system, handling several functions at the local I/O level. This distributed intelligence not only relieves the controller from unnecessary work; it also makes sure that key functions will continue even if communication with the controller is lost.

Communication is especially a concern with wireless, which is often less reliable than a wired network.

So what do you do?

Instead of programming the pump control logic in the central controller, take advantage of one of the functions built into the brain: pulsing. Have the strategy issue just one Start On-Pulse command, in this case with a 15-minute pulse duration. If the brain is cut off from the controller during those 15 minutes, it's no problem: the brain will still shut off the pump.

You may also want to set a watchdog on a remote I/O unit, so the brain will set outputs to a safe state if communication is lost. And another key item for anyone using remote I/O is an enabler chart to re-enable units if they go offline.

Questions? Comments? Contact Opto 22 Product Support.

Opto 22 an Automation World First Team Supplier

Opto 22—Your "First Team" Supplier

Automation World magazine has announced that its readers voted Opto 22 a "First Team" supplier for programmable automation controllers for 2011.

Readers chose honorees during the year through an open-ended, unaided recall survey in the Leadership in Automation section of Automation World's website.

As Gary Mintchell, the magazine's co-founder and Editor in Chief, writes: "The results are a short list of companies whom your peers go to first when they're looking for innovative solutions to their automation problems."

Thank you for your confidence in Opto 22!


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Opto 22 Product Support

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