Part of a range of controllers, the CRIUS® is the big brother of the CRONOS® and offers more sensor connections, more functionality and more flexibility with a colour screen and optional built in 3G modem. The CRIUS® is an attractively priced, top of the range instrument controller. Optional communications packages allow Profibus, Modbus ASCII, Modbus RTU, Modbus TCP and others.
The CRIUS® is equipped with the capability to connect up to four sensors of any type with appropriate analogue outputs and relays. Four sensors not enough? Simply connect up to 4 CRIUS® together all using the same display and communications. Equipped with data logging as standard and multiple PID loops as options, the CRIUS® is very able to control complex water treatment processes at a fraction of the cost of other controllers.
With all users having their own log on, and with three levels of instrument and remote access security, you can use the CRIUS® with all of its superior functionality with confidence.
The phrases ‘Water 4.0’, ‘Industry 4.0’, ‘Internet of Things’ and ‘SMART and DIGITAL’ are now commonly heard but what do they mean and where does Pi fit in? Industry 4.0 relates to the concept that we are living through a 4th Industrial Revolution where factories will be as SMART as they can be. The main principles are based on:
Water 4.0 is how this technology and philosophy will be implemented/will affect the water industry. The Internet of Things refers to all devices we use all the time talking to each other and making their own decisions.
It is generally accepted that SMART refers to the increasing sophistication of equipment to make decentralised decisions, so it is this technology that allows for the implementation of Industry 4.0 or Water 4.0, and DIGITAL refers to its comms capability. For example, in 1990 a chlorine analyser measured chlorine in water, gave out a 4-20mA output proportional to the chlorine and a couple of relays.
In 2018 the CRIUS® HaloSense (fully Water 4.0 developed) can provide the 4-20mA output and relays, but also has multiple digital comms options (interoperability), has space for up to 16 sensors (information transparency), has wireless and wired internet access (technical assistance) and full PID capability with remote setpoint, i.e. another device can set the setpoint (decentralisation).
A CRIUS® plus Sensor equals…
For each sensor the CRIUS® will prompt users through calibration procedures and will remind them when maintenance is due for each sensor type.
The CRIUS® is currently used in a multitude of applications and the remote access capability is bringing solutions to our customers’ water treatment requirements.
The CRIUS® is preferred in the Swimming Pools market, where the superior control and sensor capability provides for better quality bathing water. Again the remote access is proving essential to our customers along with the Variable Speed Drive (VSD) control which is massively reducing electricity usage and CO2 emissions (and reduces the electric bills!).
In the municipal drinking water market, the superior control capability is making it the controller of choice for areas like coagulation control with the superior sensors in use particularly for chlorine control and dissolved oxygen control.
The CRIUS® can also come in a multitude of languages making it suitable for use in any market.
Customers requiring a no-frills controller should consider the CRONOS® controller.
Small water treatment plants, secondary disinfection plants etc. tend to suffer from similar problems wherever they are in the world. The first is lack of communications SCADA infrastructure, the cost of which to install can be prohibitive. The second is the lack of a central DCS control infrastructure, again the installation of which can be cost prohibitive. The third is the remote location. Often these water treatment plants are in remote and difficult to access locations.
With these three issues facing many water engineers around the world, a low cost solution providing solutions to all three issues is available from Pi. A CRIUS® controller has the on board capacity to provide small scale SCADA, and full online PID control whilst the sensors (e.g. chlorine, pH, Turbidity etc.) are suitable for long term operation without operator intervention.
To demonstrate the remote access capability of the CRIUS® please click here.
To hear more about other customers using the CRIUS® multiparameter controllers in a similar way why not contact us?
| Document | Type | Size |
|---|---|---|
CRIUS® | Brochure | 733kB |
CRONOS® | Brochure | 712kB |
CRIUS® Remote Communications | Brochure | 669kB |
CRONOS® and CRIUS® Control Options | Technical Note | 649kB |
Water 4.0, Industry 4.0, IoT, SMART and DIGITAL | Technical Note | 711kB |
How To Specify a Pi Analyser | Technical Note | 758kB |
Remote Access GPRS | Technical Note | 593kB |
PID Control | Technical Note | 665kB |
Focus Ons are a series of short articles distributed by email providing technical information regarding instrumentation, process measurement in potable, waste, process and pool waters. If you would like to join the mailing list, please contact us.
You’ve probably heard the phrases ‘Water 4.0’, ‘Industry 4.0’, ‘Internet of Things’ and ‘SMART and DIGITAL’ but did you know that…
… Pi’s CRIUS® controller is already set up for all of these things?
… Pi already has SMART and DIGITAL installations all over the world?
… Pi works as partners to many multinational organizations to provide their remote access, remote comms and SMART technology?
Simply put the concept is that we are currently living through the 4th Industrial Revolution.
The first was mechanization, (what we currently think of as the Industrial Revolution), so steam engines, Spinning Jennies, railways, canals and factories in the 1800s.
The second was the age of mass production so; electricity, the production line, etc., largely in the first half of the 20th century.
The third was computers and automation, in the latter part of the 20th century, and the fourth?
The fourth (Industry 4.0) is about ‘SMART’ factories. (The original use of the expression Industry 4.0 was by a group of advisers to the German government who presented their advice in 2012). Industry 4.0 is about making factories as SMART as they can be. That is having assets (machines, people, robots, AI, cyber technology etc.) all communicating with each other.
The main principles put forward were based on;
Water 4.0 is simply how this technology and philosophy will be implemented/will affect the water industry. There are some clear outcomes from the above… more sensors… more modelling… ‘SMARTER’ instruments, controllers, pumps etc…
SMART and DIGITAL.
These terms aren’t quite as well defined as others. Generally it is accepted that SMART is the increasing sophistication of equipment to make decentralized decisions. For example, in 1990 a chlorine analyser measured chlorine in water, gave out a 4-20mA output proportional to the chlorine and a couple of relays.
Now the CRIUS® HaloSense (fully Water 4.0 developed) can provide the 4-20mA output and the relays, but also has multiple digital comms options (INTEROPERABILITY), has space for up to 16 sensors (INFORMATION TRANSPARENCY), has wireless and wired internet access (TECHNICAL ASSISTANCE) and full PID capability with remote setpoint, i.e. another device can set the setpoint (DECENTRALIZATION). So SMART technology is the technology that allows for the implementation of Industry 4.0 or Water 4.0. DIGITAL tends to refer to the comms capability.
When the previous Industrial Revolutions happened, the technology and concepts spilled over into the consumer world from the business/manufacturing world. With Industry 4.0 it is beginning to be the other way around with consumer demand for the internet, and mobile phone technology, driving the technology. If we assume that in this Industrial Revolution the same thing will happen, then the Internet of Things refers to all devices we use all the time talking to each other and making their own decisions.
Imagine your mobile phone waking you at 6am and telling your kettle that turns itself on at 6.20am, which tells your car that starts itself and defrosts the windscreen at 6.30am etc…
Consider this… perhaps Industrial Revolutions are only identifiable in hindsight?
And what does it matter? Well from Process Instruments’ point of view, it doesn’t. As long as our products are leading the way in providing our customers with what they need to enable their own Industry 4.0.
If you have used a Pi controller you will know that they give you unrivalled control options but did you know that Pi’s new controllers also offer individual security for up to 20 named individuals? Pi’s controllers have always given flexibility but did you know that Pi’s new controllers can accommodate up to 16 sensors of any description?
This Focus On describes the 10 most popular innovations to be found in Pi’s new CRONOS® and CRIUS®.
Both the CRONOS® and CRIUS® analyser/controller has a downloadable human readable service log – giving an entire history of the instrument including current settings, calibrations etc. Provides a great snapshot of how an engineer left an instrument.
Ever had to set up many instruments with the same settings? Simply set up one and copy it to others!
No. 3 – On screen wiring diagrams
Lost the manual or can’t be bothered to find it? Pi’s analysers have the answer!
Pi’s new sensor maintenance pages are just for you then! Detailed information about all aspects of the signal coming off the sensor clearly available.
No. 5 – Instrument datalogs not quite giving you what you need?
Pi’s new look datalogs in CRONOS® and CRIUS® (downloadable) let you datalog almost everything, put graphs on the display, datalog the same parameters at more than one interval and a whole lot more. Never has instrument datalogging been so easy and complete.
No. 6 – New enclosure
The new enclosure brings a new level of flexibility being wall mountable, pole and handrail mountable and even flush mountable. Not only that, but it gives you loads of room to work in and there are even spare live, neutral and earth terminals to make wiring relays easier!
Don’t worry, simply daisy chain 4 CRIUS® together and you can use the same display, comms options etc. and increase your I/O fourfold to give up to 16 sensors.
Pi’s new manuals are bespoke to each instrument. The manual is ‘built’ to match each individual instrument so the manual only has what you have!
No. 9 – Has the operator been messing with settings they shouldn’t?
No more! With 20 individual user settable logons, you can give people access to what they need and no more.
Pi has developed a reputation for developing great control algorithms and this has continued with the new CRONOS® and CRIUS® with the introduction of feed forward control algorithms and a master controller which selects the correct control philosophy to use (for use with complex systems such as coagulation control).
You probably know that Process Instruments offers a cloud based remote access service for our CRIUS® analyser, but did you know that…
… nearly everything you can do in front of the analyser you can do remotely?
… we have been working closely with our customers to bring you an even better service?
… a lot of our customers have seen the number of engineer callouts drastically reduce, saving them time and money?
Pi has always been a leader in developing new technology and have had a remote access system for over 10 years! The latest iteration of remote access is now a key part of our solution toolbox. Here are some of the features of our remote access:
User interface – The interface mimics the analyser, making the data and other features easy to find. Anyone already familiar with the CRIUS® analyser will already be familiar with remote access. Anyone requiring training can now be trained remotely using remote access and Skype.
User control – Each user has their own customizable access rights for what they can view and change on the analysers. This is set by the ‘parent’ user.
Speed – The service now runs around 50 times faster than its predecessor, allowing users to connect and download the current sensor values and settings in under 30 seconds (test performed on CoagSense coagulation controller with 27 different devices such as sensors!).
Reduced data costs – By making the connection between the server and analyser more efficient, Pi has reduced the amount of data required for nearly all tasks thereby significantly reducing costs.
Customer branding – On request, Pi can brand the remote access theme to promote a customer’s brand.
Data analysis – The graphical interface is a powerful and flexible tool for viewing your sensor data. The way we handle your analyser’s data means that every single data point is stored in the cloud, allowing a user to download 3 months’ worth of data with a single click.
Password reset – If a password has been lost or forgotten, a user can enter their email address into the password reset function which will then email a list of instructions on how to reset it.
Data limit – Users can now limit how much data each analyser can use per day, meaning no more unexpected data costs.
The remote access service has always been designed to save you time and money by allowing you access to the analyser and its data from anywhere in the world. Now remote access can assist as a tool in doing a lot more:
When the analyser and remote access server communicate, Pi uses a ‘Pre-Shared Key’. This creates a secure connection between the server and analyser. The key acts as a password and without it the analyser will not respond. The key is randomly generated in every analyser making it unique to each, and if required the key can be re-generated from the analyser. The analyser can also be connected directly to a Virtual Private Network (VPN) which blocks unwanted traffic and connections automatically and will only transfer information between the analyser and server.
Each user has their own username and password. This means that what they see and what they can do can be customized so only authorized users can make changes.
If a user creates a group, then they become that group’s ‘parent’. The ‘parent’ of a group creates the analysers and users for that group. If a user is a ‘parent’ to more than one group, they will also have the ability to create users that can access multiple groups from a single user account.
Did you know…
… that PID can save you money by offering better process control?
… that PID can help you maintain a setpoint, even with a variable process?
… that the days of over complex and confusing PID are over?
… that Pi can tailor a PID system to your exact requirements? You may never have to touch those settings again!
In this Focus On, Pi would like to introduce you to PID if you haven’t come across it, and discuss some of the useful advanced features of modern PID systems, like on Pi’s CRONOS® and CRIUS® models for those more familiar with PID.
PID is a mathematical tool created by engineers and is used in controllers. It is a feature often found in industrial controllers and is available in Pi’s controllers, as an inexpensive upgrade.
The best way to explain what PID does, is to take an example. Most people have been to a swimming pool at some point in their lives, so this is the example we shall use. PID is also applicable in a huge variety of other processes. If you are not sure, you can always contact us to discuss your application.
When a person enters a swimming pool, they create a chlorine demand. They do this by introducing sweat, bacteria, organic molecules and other substances into the pool water. Chlorine reacts with these substances, which results in chlorine being used up and the chlorine level dropping. The chlorine level in this example, is often called the process variable or PV in the context of PID.
In order to maintain a concentration or level of chlorine, more chlorine needs to be dosed. If you dosed the same amount of chlorine per bather, the level would not be stable as all bathers create a different chlorine demand (e.g. swimming for fitness produces more sweat than swimming recreationally). Dosing manually brings in the issue of human error, and how operators approximate or calculate the amount of chlorine to dose based on current levels. Another issue with manual dosing is that it is not a continuous process, meaning it is unlikely a stable level will ever be reached.
PID takes the measured level of chlorine or the PV and compares it to the desired level or set-point. This comparison gives the error which PID interprets and then calculates an output. The output is an electrical signal which controls the dosing of the appropriate chemical. The output can control heaters, dosing pumps and many other mechanisms that can be used to change the PV.
PID is made up of three parts, proportional, integral and derivative. Understanding what each part does helps operators choose the level of control best suited to them.
Proportional – Is the most commonly used for portion PID and suits most applications. When using proportional control, the further away the measured value is from the setpoint, the larger the output will be from the controller. This is an appropriate level of control for most processes, and users can gain a lot of control from a purely proportional system.
In some systems where the PV is lost to the process, e.g. chlorine from a pool, heat from a boiler etc., the proportional control never quite catches up with the setpoint. Users can see that although the process approaches the setpoint it rarely, if ever, gets to it. This is known as ‘droop’. The user can compensate for droop if the removal of the PV is fairly constant, simply by raising the setpoint, e.g. evaporation of chlorine from an empty pool. If droop changes often, (e.g. bather load or chlorine demand) then to eradicate the ‘droop’ then the integral part of PID can be applied to the signal to correct it.
Integral – The output from the integral term is determined by both the magnitude and the duration of the error. A small error over a long period of time will trigger a larger response than from a purely proportional system. This helps the elimination of the ‘droop’ seen in processes with continuous loss, and also serves to help reach the setpoint quicker.
Derivative – Derivative gain is rarely used and is generally set up only by expert engineers. Derivative gain uses the rate of change in the PV to try to predict future errors. This type of control is particularly susceptible to overcompensating, especially if there is even a small amount of signal noise (usually seen as spikes in the PV). Derivative gain is generally a tweak used by engineers to improve an already tight control, and is almost never used as an essential part of control.
When properly set up, PID can lead to far tighter process control, which in turn can save you time and money. As an example, pool managers want to keep chlorine levels low, to improve the bathing experience and also save on chemicals. AquaSense is a chlorine analyser system that responds quickly and appropriately to a change in bather load (also known as chlorine demand). This means pool operators can save money whilst maintaining the safety of the pool. PID can also help reduce the risk of overshooting the desired setpoint, reducing the risk of dangerous overdosing of the chemicals.
Whilst maintaining a setpoint with a PID loop is a huge advance over using threshold relays to maintain an upper and lower limit, it is sensible to control the loop with extra safeguards, such as:
These are all standard features in all Pi PID controllers.
In summary, PID is a very useful tool when used correctly, and can result in significant chemical savings, not to mention reduced pump wear and tear and lower electricity costs.
Process Instruments (Pi) are increasingly seeing water engineers and technicians relying on their PLC’s PID auto-tune feature. Many are becoming frustrated that the auto-tuners are unreliable when it comes to water processes. Sometimes the auto-tuned PID settings work, but then something changes in the process and the PID control no longer functions correctly.In this Focus On, Pi aims to outline how PID auto-tuners work and why they are often unsuitable for complex water treatment processes. We also give a brief introduction to some of the principles of tuning a PID manually.
Did you know that…
…auto-tuners are not effective at tuning processes with long loop times?
…the CRONOS® and CRIUS® have many built-in PID safety features to make control easier and safer?
…PID loops can often be tuned remotely, meaning huge savings on site visits and travel time?
A Proportional – Integral – Derivative (PID) controller is a control loop feedback mechanism widely used in industrial control systems. PID controllers allow a system to continuously and automatically modulate a control mechanism (e.g. a dosing pump, a valve, motor speed), to attempt to achieve a desired setpoint.
There are a myriad of ways that a PID controller can be ‘tuned’. In a very basic PID controller, the operator can choose how much of their control should be based on P, I and D. In reality, D is almost never required in water processes due to the nature of the control loop.
This is generally what ‘auto-tuners’ undertake. They make small changes to the ratio between P, I and D control, track the response, decide if the change is good or bad, and then change again.
So what the auto-tuner is doing is changing, measuring, and changing again; which can work perfectly on processes with a very short loop time (time between a change and a response from the system), the auto-tune making many changes in a short amount of time. The changes cumulate into a ‘tuned’ PID system.
Below is an example system of a PID auto-tune.
In the diagram, we can see that for the system to work, the box in red is a crucial part of the process. If the change brought on by the PID auto-tuner isn’t visible quickly enough, it may affect the way the auto-tuner categorises the change (good or bad), or won’t give the auto-tune the opportunity to make enough iterative changes to bring a complex water system under control.
There is good news for water technicians and engineers and that is that Pi are here to help. All our salespeople are application specialists and are all capable of helping you manually tune a PID controller for your processes. Our CRONOS® and CRIUS® controllers are both capable of delivering excellent control in many processes, and have many built-in PID features to help make your process more controlled, robust and safe.
In many ways, the auto-tuners mimic plant engineers making adjustments and tuning their PID settings. They simply lack 2 key components;
With this in mind, here is how our engineers approach PID tuning on our instruments;
Once you have the basic P and I ratio sorted, or if you are unable to get the P and I into control, it is worth considering these additional settings which will help make your control scheme more robust and safer.
Even armed with all this knowledge, PID tuning can be a bit of a dark art. What works on one site may not work on another and even experienced engineers sometimes call us for help.
One of the ways we can help is using Remote Access. Our Remote Access portal allows people with the appropriate security clearance to make changes to settings and observe measurements from their desk.
Sales Manager, Dr. Rob Paramore, recently described his experience of changing a customer’s PID settings (at their request), whilst talking them through what he was doing on the phone:
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