We talked about sinking and sourcing in a previous OptoNews tech tip.

But it's a subject that causes a lot of confusion, so it's worth revisiting.

Sinking and sourcing basically refer to the two methods of wiring a digital DC circuit.

Topics: Discrete control, Tips, optonews, I/O, OptoNews 2015-11-04

Let's say you have four pumps available, and you don't run them all at once. When it's time to start one, you want to choose the one with the least wear. 

You can decide which one to start by comparing the total amount of time each pump has run. That's a job for a totalizer.

Topics: Tips, optonews, PACs, I/O, PAC Project, OptoNews 2015-10-21

A SNAP PAC controller communicates over Ethernet. Is it OK if two PCs are trying to communicate with the PAC at the same time, or will they interfere with each other? 

This was the question in a recent OptoForum post, and it got a quick answer: yes, it's OK.

Whether it's a standalone S-series or a rack-mounted R-series PAC, you can have many devices simultaneously requesting data from and sending data to a SNAP PAC.

Topics: Tips, optonews, PACs, Integrators, Networking, OptoNews 2015-10-07

When you turn on an output, do you set a flag and then check it to see the output's status before turning the output on again? 

Or do you just turn it on without checking?

Is setting a flag a good way to speed up the program and avoid tying up the network with unnecessary communications to I/O?

Or does it just add a lot of extra variables and decision blocks that make debugging and maintenance harder?

Topics: Discrete control, Tips, optonews, PACs, I/O, PAC Project, OptoNews 2015-09-23

In the last OptoNews we talked about using date and time in PAC Control. (If you haven't seen the post, be sure to check out its links to useful resources.)

Meanwhile, Opto 22 customer Philip Spigelmire was busy writing a scheduling subroutine for his HVAC system. His subroutine handles:

Topics: Energy management, Tips, optonews, PACs, PAC Project, Building management, OptoNews 2015-09-09

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The Case for Intelligent I/O Systems.

The automation PC is located in the control room, and the dump valve is on the other side of the tank farm wired to a remote I/O cabinet, all connected over an Ethernet network.

The IT guys are working on the network, and they say it may take a few days to track down the intermittent cable. But hey, in the meantime, they say that it mostly works…

That answer might be sufficient for watching YouTube, but it is just not going to cut it for controlling that valve.

What do you do?

Topics: Discrete control, PLCs, Remote monitoring, Tips, IoT, PACs, OEM, I/O

Lately we've received some questions about one of the key concerns in control: controlling something at a specific point in time. 

• Maybe you want to turn on a pump at 6:00 a.m. every day
• Or start a process on Tuesday
• Or restart a count at midnight on the last day of each month

This tip pulls together some resources for control based on time, day, and date. 

Topics: Process control, Discrete control, Tips, optonews, PACs, PAC Project, OptoNews 2015-08-26

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Do what when:

In last week’s blog we covered how to set the real time clock (RTC) in a PAC Controller with an accurate time server over the Internet using SNTP.

Now that our controller knows exactly what time it is, how do we turn on that pump at 6:00 a.m. on the dot?

Like most aspects of programming, there are a few different ways to achieve the same result, so join me in this week’s blog while we look at one way to manage real-time scheduling.

Topics: Energy management, Process control, groov, Internet of Things, Tips, IoT, PACs, PAC Project

Do you use PAC Control? If so, you'll want to watch these handy tips in video format, all showing you step-by-step tips for Opto 22's control development software.

The videos are quick to watch and helpful no matter how long you've been using PAC Control.

Some examples...

Topics: Videos, Tips, optonews, PAC Project, OptoNews 2015-08-12