TPS-based aircon controller

Air conditioning is a consumptive business while air conditioners are big-ticket to run. In general, AC systems, older ones, in particular, do not have any real temperature feedback. You set the temperature on your remote, but alas, it has absolutely nothing to do with the actual temperature in the room. Even when it gets colder outsides, many aircons keep blasting cold air into your space. As a result, you have to constantly readjust the temperature as needed for optimal comfort throughout the day.

No doubt, AC systems are improving day by day, but there are still old systems that cannot get updated. In some instances, it’s absolutely impossible to invest in a new system. Sometimes, it is just a catch 22 to rip the old aircon out and install a new one. A basic aircon has many parts that typically are split between an outside and inside configuration, hence you may have to undergo a drastic interior renovation. In Tibbo office in Taipei, we have got trapped in an identical situation. We just have to get by with the AC system we’ve got. Our aircon is controlled with a dozen of infrared remotes lying around.

Some time ago, we set out to create a management system for our dated HVAC system. We used Tibbo Project System (TPS) for this endeavor. Our spec for the aircon controller consisted of exactly two items:

• The aircon must run or not run depending on whether the lights are on or off. The formula is simple: no lights = no people = no need to run the AC.
• The temperature in the room must be monitored by the device that stops the aircon whenever the temperature is cooled off to the preset point.

To achieve our goal, we used a TPS2L system equipped with these Tibbits:

• Ambient temperature probe
• IR code processor Tibbit (#26)
• IR front-end Tibbit (#27)
• Ambient light sensor Tibbit (#28)

Let us tell you about the probe.The probe replaces the ambient temperature meter (Tibbit #29). It is nice to have the meter built right into the TPS. The problem is, the meter is affected by the internal heat of the TPSsystem itself. This influence is especially noticeable for the TPS2L device – it’s LCD really warms up the box! The new probe has the same circuit as the Tibbit #29, with the added benefit of being external to the TPSdevice. Now the measurements are accurate.

Here is a look at the items you need to set up in the menu:

IR commands. This is where you train your IR code processor to be able to transmit two commands: “On,” and “Off.” For the “On” command, use the lowest temperature that your aircon’s remote allows you to set (usually 16 degrees C). The logic here is that when you need to lower the temperature in the room you can use the coldest temperature setting, and when the room cools down to the preset temperature, the aircon is turned off. So really, you only need two commands.

Target temperature. You don’t need to set it here. There are dedicated buttons on the main screen.

Pre-cool start time. This is something we added along the way. Now it is possible to turn the aircon on, once a day, even before we all arrive at the office. Our day starts at 9 am. We set this time for 8:30 am, and by the time we get in, the office is nice and cool (while the scorching Taipei summer keeps on raging outside). The pre-cool timer is hardcoded for 45 minutes. If the lights are still off at 9:15 the aircon is turned off.

*Brightness threshold. *This is the brightness that the TPS will consider to correspond to “lights on.” The value is not expressed in any standard measurement units; it’s just the value the Tibbit #28 returns. So, how do you know what number to set here? Simple: the brightness is displayed on the main screen, like this: “Light level: 718”. Note the value with the lights off and on, then set the threshold to some value in the middle between the two.

Temp. meas. adjustment. This is useful for when you choose to use the Tibbit #29. As we’ve explained above, its measurements are affected by the internal heat of the TPS itself. You can use a regular thermometer and determine the measurement error. For example, if your thermometer reads 25C, and TPS shows 28C, then you must adjust the temperature by 3 degrees C. The data returned by the new external probe need no adjustment.

Further work

In phase 2 of this project we will connect our aircon controller to an AggreGate server. It will be possible to control the system via a smartphone app, which we going to design for this purpose. Now you know why our configuration menu has items like Network, AggreGate, etc. Stay tuned!

Figure 2  Aircon

Tibbo Project System (TPS) is a highly configurable, affordable, and innovative automation platform. It is ideal for home, building, warehouse, and production floor automation projects, as well as data collection, distributed control, industrial computing, and device connectivity applications.

Suppliers of traditional “control boxes” (embedded computers, PLCs, remote automation and I/O products, etc.) typically offer a wide variety of models differing in their I/O capabilities. Four serial ports and six relays. Two serial ports and eight relays. One serial port, four relays, and two sensor inputs. These lists go on and on, yet never seem to contain just the right mix of I/O functions you are looking for.

Rather than offering a large number of models, Tibbo Technology takes a different approach: Our Tibbo Project System (TPS) utilizes Tibbits® – miniature electronic blocks that implement specific I/O functions. Need three RS232 ports? Plug in exactly three RS232 Tibbits! Need two relays? Use a relay Tibbit. This module-based approach saves you money by allowing you to precisely define the features you want in your automation controller.

Here is a closer look at the process of building a custom Tibbo Project System.

Start with a Tibbo Project PCB (TPP)

A Tibbo Project PCB is the foundation of TPS devices.

Available in two sizes – medium and large – each board carries a CPU, memory, an Ethernet port, power input for +5V regulated power, and a number of sockets for Tibbit Modules and Connectors.

Add Tibbit® Blocks

Tibbits (as in “Tibbo Bits”) are blocks of prepackaged I/O functionality housed in brightly colored rectangular shells. Tibbits are subdivided into Modules and Connectors.

Want an ADC? There is a Tibbit Module for this. 24V power supply? Got that! RS232/422/485 port? We have this, and many other Modules, too.

Same goes for Tibbit Connectors. DB9 Tibbit? Check. Terminal block? Check. Infrared receiver/transmitter? Got it. Temperature, humidity, and pressure sensors? On the list of available Tibbits, too.

Assemble into a Tibbo Project Box (TPB)

Most projects require an enclosure. Designing one is a tough job. Making it beautiful is even tougher, and may also be prohibitively expensive. Finding or making the right housing is a perennial obstacle to completing low-volume and hobbyist projects.

Strangely, suppliers of popular platforms such as Arduino, Raspberry Pi, and BeagleBone do not bother with providing any enclosures, and available third-party offerings are primitive and flimsy.

Tibbo understands enclosure struggles and here is our solution: Your Tibbo Project System can optionally be ordered with a Tibbo Project Box (TPB) kit.

The ingenious feature of the TPB is that its top and bottom walls are formed by Tibbit Connectors. This eliminates a huge problem of any low-volume production operation – the necessity to drill holes and openings in an off-the-shelf enclosure.

The result is a neat, professionally looking housing every time, even for projects with the production quantity of one.

Like boards, our enclosures are available in two sizes – medium and large. Medium-size project boxes can be ordered in the LCD/keypad version, thus allowing you to design solutions incorporating a user interface.

Unique Online Configurator

To simplify the process of planning your TPS we have created an Online Configurator.

Configurator allows you to select the Tibbo Project Board (TPP), “insert” Tibbit Modules and Connectors into the board’s sockets, and specify additional options. These include choosing whether or not you wish to add a Tibbo Project Box (TPB) enclosure, LCD and keypad, DIN rail mounting kit, and so on. You can choose to have your system shipped fully assembled or as a parts kit.

Configurator makes sure you specify a valid system by watching out for errors. For example, it verifies that the total power consumption of your future TPS device does not exceed available power budget. Configurator also checks the placement of Tibbits, ensuring that there are no mistakes in their arrangement.

Completed configurations can be immediately ordered from our online store. You can opt to keep each configuration private, share it with other registered users, or make it public for everyone to see.

Develop your application

Like all programmable Tibbo hardware, Tibbo Project System devices are powered by Tibbo OS (TiOS).

Use our free Tibbo IDE (TIDE) software to create and debug sophisticated automation applications in Tibbo BASIC, Tibbo C, or a combination of the two languages.

To learn more about the Tibbo Project System click here

OPC – «Open Platform Communications» – is a set of standards and specifications for manufacturing telecommunication. OPC specifies the transfer of real-time plant data between control devices from various producers. OPC was designed to process control hardware and support a common bridge for Windows-based software applications. OPC was aimed to reduce the number of duplicated effort performed by hardware manufacturers and their software partners.

The most typical OPC specification, OPC Data Access (OPC DA), is supported by Tibbo OPC Server. Any device compatible with the Tibbo AggreGate protocol can be a data source. AggreGate is a white-label IoT integration platform using up-to-date network technologies to control, configure, monitor and support electronic devices, along with distributed networks of such electronic devices. It also helps you collect device data in the cloud, where you can slice and dice it in alignment with your needs. In addition, the platform lets other enterprise applications transparently access this data via the AggreGate server.

Tibbo OPC server has embedded AggreGate network protocol. It can both interact with any Tibbo devices via AggreGate agent protocol and connect to AggreGate server. The AggreGate agent protocol open-source solution is published for Java, C#, and C++ programming languages, so your connection scheme is not restricted to AggreGate server  or Tibbo devices only.

Examples

A simple example: TPS reads Tibbit #29 (Ambient temperature meter) and forwards data to OPC server via AggreGate agent protocol.

A more complex example: we have a Windows-based PC controlling a wood processing machine by means of AggreGate server through the Modbus protocol. If Tibbo OPC server is linked with AggreGate server, the data from the machine is sent to Tibbo OPC server, and therefore, we can operate and monitor the machine via any OPC client.

Technical Specification

• Compatibility with Windows XP/2003 or later (Microsoft Visual C++ 2013 redistributable is required - installed automatically)

• Support of DA Asynchronous I/O 2.0 and Synchronous I/O with COM/DCOM technology

Tibbo OPC Server transmits the information on the Value, Quality and Timestamp of an item (tag) to the OPC Client applications. These fields are read from the AggreGate variables.

The process values are set to Bad [Configuration Error] quality if OPC Server loses communication with its data source (AggreGate Agent or AggreGate Server). The quality is set to Uncertain [Non-Specific] if the AggreGate variable value is empty.

In the following chart below you can see a concordance table of the AggreGate variables and the OPC data types:

To learn more about Tibbo OPC server, click here