FEATURE ELECTRICAL & ELECTRONIC COMPONENTS
Networking and wiring solutions for automation systems
S
ensors and actuators in automation systems used to be connected individually to a central
control panel, sometimes directly and sometimes via local terminal boxes. Not only did that mean a lot of field wiring, but such systems were difficult and time consuming to install, with wiring errors often extending the commissioning time for new plant – sometimes by weeks. So when fieldbus systems arrived around 30
years ago, they were warmly welcomed by the automation sector. But while these reduced the amount of field wiring needed, early versions often had technical limitations. The survivors and their direct descendants, however, continue to give good service today. Despite this, there are some niggling
issues with fieldbus solutions that have been around for so long that they’re almost taken for granted. These, however, have been successfully addressed by recent developments.
RECENT DEVELOPMENTS The key to many of these developments is the emergence of the IO-Link protocol which is easily integrated into sensors, actuators, and other devices. It is vendor neutral and is supported by most of the leading suppliers of sensors and other field-mounted devices. Put simply, the IO-Link protocol enables point-to- point two-way communication between what would previously have been simple sensors, actuators or I/O blocks. There are several key benefits. The first is
the ability to add an IO-Link device to a new or existing system and parameterise it without the complexities that are usually associated with adding intelligent or smart devices. The second is that an IO-Link device can automatically give the user additional diagnostics down to sensor level without the need for extensive coding in the PLC. Finally, the replacement of a faulty device is simplified as the new device is recognised and its parameters loaded automatically. This eliminates errors and makes it unnecessary for replacement work to be carried out by skilled technicians. Fieldbus modules are available with ‘IO-Link
master ports’ which let you connect up to eight IO-Link devices to an existing fieldbus installation. There are versions to suit all of the most popular fieldbus systems – so, if you are using EtherCat, for example, you can use one of these modules to make a direct connection between your IO-Link devices and your EtherCat fieldbus.
22 DECEMBER/JANUARY 2021 | DESIGN SOLUTIONS
Tim Dodd of ifm electronic looks into the latest solutions for automation networking and wiring
A recent development, configurable IO-Link
I/O modules, solve a longstanding fieldbus system design problem. In the past, if the I/O modules in a particular system had eight channels – which is fairly typical – that was fine if you needed, say, eight digital inputs or eight analogue inputs in a given location. But what would you do if you needed four digital inputs and four analogue inputs? Usually the answer was that you had to buy an eight-channel digital input module and also an eight-channel analogue input module then leave half the channels on each unused. Clearly this increases costs. With a configurable IO-Link I/O module,
however, any of the eight channels can be set to operate as a digital input, an analogue input or a digital output. So, if you want four digital and four analogue inputs, or three digital inputs, two analogue inputs and three digital outputs, or any other combination of eight channels, one module is all you need. As this module is an IO-Link device you can connect up to eight of them to the new generation of fieldbus modules discussed earlier, which means that a large amount of I/O can be connected to a single fieldbus module. If you need to send data from your sensors
to an ERP system, or similar, as well as to your control system, there are IO-Link modules that will help with this. They have two network interfaces, one of which can be used for a link to the control system while the other is connected directly to the ERP system. With this so-called Y configuration, data for the ERP system doesn’t have to pass through the control system, which decreases the load on it as well as simplifying the programming required. Because IO-Link was developed from the
outset for automation applications, IO-Link I/O modules support the connection of up to eight IO-Link devices. The devices are connected to the module using standard pre-configured sensor cables, which cuts wiring time dramatically. In addition, the modules are available in versions with high IP ratings which can be mounted directly on the plant without the need for further protection. Modules manufactured from materials suitable for use in the food industry are also available, and these are unaffected by washdown cleaning methods.
/ DESIGNSOLUTIONS
SAVING MONEY In today’s industrial environment, fieldbus and network systems are often the most satisfactory and economical choice for connecting field-mounted devices. However, very simple standalone systems and machines may not benefit from the features offered by fieldbus connections – ordinary wired connections directly to the control system may be all that’s needed. Even in these cases, however, there are
developments that can save money and make life easier. For example, splitter boxes with high IP ratings are available that make provision for the connection of multiple field-mounted devices – typically up to eight – using standard pre-manufactured cables with plug-in connectors. The splitter box is then connected to the control panel with a single multicore cable. The splitter boxes take up very little room on the plant and need no additional protection, yet they greatly simplify wiring and make maintenance easier as, if it is necessary to replace a field-mounted device or its connecting cable, all of the connections simply plug in. And even for these simple systems, useful accessories are available such as T-splitters which allow a connection that would normally serve just one field device to serve two. As we have seen, wiring systems for field-
mounted devices have come a long way in the last two or three decades, but to get the best from them it’s important to stay on top of recent developments, even in simple systems where a fieldbus implementation isn’t appropriate.
ifm electronic
www.ifm.com/uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
