UK manufactured controllers less expensive than those from
the Far East (added:
How custom are our customised electronic controllers? (added:
Stop the machine, it's getting too hot! (added:
Are touch-screens any good? (added:
My temperature controller is discombobulated! (added:
Saving time and money by simplifying machine wiring (added:
Testing times (added: 9/2/2012)
To PLC, or not to PLC, that is the question.(added:
Saving Energy with Temperature Control
UK manufactured controllers less
expensive than those from the Far East
added: 27th April 2013
We have just started manufacturing a temperature controller for a client
who has a requirement for 50 units per month. Until now, they have been
using a low cost, off-the-shelf temperature controller, mass-produced in
the Far East. Our client was astounded to find our solution saved nearly
£10 per unit.
So what is the secret? We can assure you that Cambridgeshire labour
rates are certainly not lower than those in the Far East. We can also
say with confidence that our UK manufactured bare PCBs are considerably
more expensive. Our overheads are higher and the economies of scale are
such that manufacturing a batch of several thousands units will always
be cheaper than producing only 50 units. The answer is fitness for
The Top Hex design does exactly what the client wants. The off-the-shelf
solution has various features that may be useful to others, but are an
expensive luxury to our client. Removing these components takes away
some significant costs. The benefits don't end there. The Top Hex
controller is finished off with an attractive overlay designed with our
clients branding improving the appearance of the machine. It is even
more significant to note that the Top Hex design reduces machine wiring
allowing our client to produce more units in less time.
With a saving of £10 our client could just about afford to buy a pint in
How custom are our customised
added: 12th April 2013
We are often asked if we start with a blank sheet of paper on every new
design? The answer is emphatically no. So, are all out designs basically
the same? The answer is also a no. And finally, will technology that has
been developed for our electronic controller be used on designs for
other clients? You have probably spotted the pattern, the answer is once
again no. So how do we do it?
The designs we produce consist of building blocks that we have developed
over many years. Think of them as a bucket of Lego waiting to be built
into a model. The advantage of using building blocks, is that they are
proven technology to us which eliminates much of the risk of a new
design. It also means we can produce a design very quickly
But what if we don't have exactly the circuit for a design? Although it
would be an exaggeration to say that we have covered all possibilities,
it is very rare that we come across something completely new. We can
usually modify one of our standard building blocks (and don't you wish
you could do this with Lego!). Meanwhile in the background, we are
working on new building blocks which may or may not be useful in the
future, keeping abreast with technology.
Stop the machine, it's getting too hot!
added: 23rd February 2013
Many systems with temperature control have an over-temperature cut-out.
In the event of a catastrophic failure, the machine will shut down
before it becomes dangerously hot. It is good practice that this
over-temperature cut-out is independent of the main temperature control.
Recently we have designed a number of controllers where this function is
fitted to our controller - but how can this be independent?
Firstly, the cut-out circuit uses a different temperature sensor from
the one used for temperature control. It does not matter with this an
RTD, thermocouple, thermistor or whatever. Secondly, on the circuit
board the over-temperature circuit is completely separate from the
processor and uses a conventional circuit to shut-off the power. So in
the unlikely event that the processor failed, the over-temperature
circuit would continue to function. The over-temperature control is
There are some significant advantages of this approach. The amount of
wiring in the control panel is vastly minimised as there is no
intermediate wiring between a temperature controller and the
over-temperature device. Best of all, the operation of the
over-temperature circuit can be cross-checked so this were to fail (and
we are now talking ridiculously unlikely probabilities), we would know
about it. Can you imagine pulling your reserve parachute, only to find
it wasn't working? Not with a Top Hex controller!
Are touch-screens any good?
added: 23rd January 2013
We have been working with a client who is looking to replace a
touch-screen human machine interface (HMI) - the sort that plugs into a
PLC. He has experienced tremendous reliability problems with this
touch-screen and wanted to know if touch screens are any good for
industrial applications? The answer is yes, but only in the right
application. He was using the touch-screen to start and stop the machine
- we have replaced these with pushbuttons. Old-fashioned maybe, but
rugged, hard-wearing and ideal for this application. Our controller
design does have a touchscreen and this is used to configure the
machine. There is nothing wrong with touch-screens, but you have to
match the technology with the application.
My temperature controller is
added: 1st October 2012
Earlier today, we took a support call from a client for whom we have
designed an electronic controller which replaced several 1/16 DIN
temperature controllers and an awful lot of wiring. However, we assist
our client by supporting the legacy control system even though we were
not involved in the manufacture of these particular units. Our client
described his temperature controller as being discombobulated - the
temperature was fluctuating wildly with the heater going on and off
seemingly at random.
On the new control system, we have programmed in dozens of fault
conditions which bring up an alarm code on the numeric display. The
alarms correspond to thermocouple open circuit, heater over temperature,
heater not warming up etc. etc. Unfortunately, the temperature
controllers could provide none of this information. The client was quite
correct, the temperature controller was discombobulated and it was
virtually impossible to deduce anything further.
After several hours of replacing components, the client discovered the
thermocouple had a loose connection and was going open circuit. Had the
Top Hex controller been used on this machine, we would have deduced this
in less than a minute.
The conclusion - if you want to avoid being discombobulated, allow Top
Hex to design a controller for you!
Saving time and money by simplifying
added: 24th September 2012
We have recently been involved in a number of projects where we have
designed a circuit board to replace wiring in a machine or control
For example, we have been working with a client who was producing a
machine with four temperature control zones. On the fascia of their
machine, they had four independent temperature controllers. There was a
large amount of wiring between these temperature controllers to manage
the warming up and cooling down sequence of this machine. It took an
enormous amount of time to complete this wiring which was complex and
therefore prone to error. Finding a wiring error often took even longer
than wiring the machine!
We have designed a circuit board replacement for this wiring and are
supplying pre-made cables, so the client only has to plug in 8
connectors. We have also added the isolating transformers for the
temperature controllers to the circuit board along with the 24V power
supply for the machine and the machine safety circuit. The result, a
smaller, tidier control panel and a significant cost saving.
But to our surprise, saving cost was not the objective of this exercise!
The client wanted to produce more machines with existing resources due
to an increase in orders. In a challenging economic environment, we are
hearing more good news.
added: 9th February 2012
At Top Hex, we like to say that everything we supply is second hand. By
this, we mean that every controller that goes out of the door has been
functionally tested. I wanted to explain why we do this, the most common
reasons that a controller will fail and what we then do to put it right
before it gets to the client.
During the manufacturing process, there are various stages of inspection
and test. However, the final test that is carried out at Top Hex is a
functional test. During the functional test, the controller is powered
up and run in a mode which is as similar as possible to the operating
conditions for the product. There is a certain poetic license in this -
for example we have a 9.0kW heater controller (see
news story) and it is not safe or feasible to put 40A @230V through
the output circuit, but we do simulate a load.
There are several reasons why a controller may have a fault. Although
all circuit boards are tested before they are shipped to us, there is a
tiny possibility a fault has not been picked up. Electronic components
are pretty reliable, but there is still a small chance that a component
is faulty, maybe from the manufacturing stage or possibly if handled
badly in the supply chain. There is also the possibility that the wrong
component has ended up in the wrong place or that the solder joint is
poor - which can either be a human or a machine error. With a skilled
workforce, this doesn't happen very often either.
So why bother? In testing a batch of 100 controllers, it would not be
unusual for all 100 to pass first time. Although we are able to automate
much of the testing process, it can be tedious and it is certainly
From our point of view, we accept that although we may be supplying a
£100 controller, it may be fitted to a £100,000 machine and be shipped
overseas. The implications of a controller being faulty can often be
horrendous and we would rather not take this risk.
If a controller does fail the test, the solution is simply to swap the
faulty part or correct the soldering and to completely re-test, in case
the repair has created a further fault. The possibility of this
happening is remote, in fact we can't actually remember it having
happened. However, when testing, you can't be too careful!
To PLC, or not to PLC, that is the
added: 16th January 2012
A question that I am frequently asked is whether a Programmable Logic
Controller or 'PLC' is the best solution to controlling a machine or
system or if it is worth considering a custom designed electronic
controller. At Top Hex, we use both solutions and in my opinion, the
decision as to which is the most suitable is usually clear-cut. In this
blog, I have set out some golden rules which I use and hope will point
you in the right direction.
The most important consideration is whether you will be supplying the
control system again in the future. If the system is a "one-off" then a
PLC is undoubtedly the best solution. I would suggest that if you can
imagine ordering 3-5 controllers at a time, then it's time to consider a
customised electronic controller. The problem with an off-the-shelf PLC
is that you will paying for features that are of no benefit to you but
may be useful to somebody else. For example, most PLCs have a
real-time-clock which adds several pounds of cost - great if you want to
know what time it us - otherwise a waste of money!
Often the best approach is to rationalise your design wherever possible
and look for similarities between systems. If you can treat each new
system as a "variation on a theme" then you can potentially be running
standard software and saving yourself a great deal of effort. Many of
the electronic designs we produce for our clients allow enormous
variations between systems. For example. we have recently designed a
temperature control system which allows for between 1 and 255 channels -
this should cover most eventualities!
The other advantage of a customised controller is that it is possible to
make some significant cost savings by including external components on
the circuit board. Power supplies, safety relays, temperature
controllers and even power switching contactors can all be included in
the design and will cost a lot less if they are fitted to the circuit
board. Best of all, you can save time and money on wiring as there will
be no cables required between these components.
If you are looking to interface with a PLC manufacturer specific
communications protocol then most likely, the PLC will be your best
option. If you want to include a standard interface such as an Ethernet
port or a USB port then you are likely to find that the customised
electronic is going to be more flexible and indeed less expensive.
Ultimately, there is very little difference in technology between a PLC
and a custom electronic controller. I like to think of a customised
controller as being a PLC with exactly the right combination of inputs
and outputs for your system. From experience, it doesn't really matter
whether the decision is made on a technical or a cost basis as the
answer is usually the same! Please let me know if I can help provide you
with the tools to make this.
Saving Energy with Temperature Control
added: 3rd January 2012
We have recently developed a controller which controls
an electric heater in an enclosed space – e.g. an office or industrial
unit. The controller takes a temperature reading from a room temperature
sensor and also close to the heater. The temperature control software
uses a version of our self-tuning temperature control algorithm which
adapts the control parameters to achieve the optimal possible
The system was tested in a typical environment and our
client carried out comparative tests using a leading competitors BMS
controller. We knew our adaptive temperature controller was good, but we
didn’t realise quite how good!
The Top Hex controller consumed 20% less electricity
than the leading competitor in maintaining the required room
temperature. After patting myself on the back for a few moments, the
engineer inside me kicked in and I am able to substantiate the dramatic
efficiency savings we were able to achieve.
The competitor’s controller uses a PID based algorithm
which works reasonably well at warming up the room and minimising the
overshoot, to an extent at least. However, the real differences were
clear when the environment changed – for example when a door was opened
or when the sun shone through the window. The Top Hex temperature
controller adapted its response to cope with the changes parameters. It
is almost like it is carrying out a critical assessment of its response
and learning from its mistakes.
However, the competitors controller doggedly stuck to
its guns using a set of parameters that suited a situation which no
longer existed. As the Top Hex temperature controller was continually
optimising its response, it used less energy in the process, minimising
the over and undershoots that dog conventional controllers. It is also
worth pointing out that unlike the competitor’s product, the Top Hex
designed controller does not need to have separate winter and summer
settings – it simply adapts to suit the season.
We know from experience that the Top Hex self-tuning
algorithm works equally well in multi-zone heater control applications,
fast and slow responding systems (particularly in cooling applications)
and even in non-temperature control for say humidity or pressure. If you
have an application you would like to discuss, please email me at