FDT technology for amplifiers
- At the core of FDT technology are so-called Device Type Managers (DTM), the drivers that make a standardized interface available.
In 2003, a number of prestigious companies in the automation sector established the FDT Group, in order to create a common communications and configuration interface for field devices in automation technology. We now have so-called DTM, the device drivers in this technology that play a crucial role for thousands of different field devices – including digiCLIP amplifiers from HBM.
Field Device Tool technology (FDT) ensures the standard parameterization of different field devices from a variety of manufacturers. It is essentially an interface definition, to simplify the engineering process in automation technology. At the core of the technology are the so-called Device Type Managers (DTM), made available by the manufacturers of field devices as standardized drivers.
This unified interface makes it possible, with just one tool, to integrate any devices into a system, whatever their manufacturer or fieldbus protocol. Only one relevant DTM has to be made available with the particular device. In certain ways, this is similar to the popular Plug&Play concept from the world of PCs, where a driver is supplied with every device, such as a printer, to allow the device to be addressed from the operating system.
FDT is for measurement technology too
- The DTM is used to parameterize all the amplifier functions, run a device diagnosis, and also implement a stripchart, for example.
Measurement technology specialist HBM has now developed a relevant DTM for its digiCLIP amplifier, and is making this available to users. Digital amplifiers are ideal for automation applications in an industrial environment.
Noise-free and stable measurement technology is a feature of the modules, and delivers extremely high-quality measurement. The carrier-frequency modules provide reliable, noise-free measurements of variables such as force, strain, torque and pressure.
Each module has a Profibus DP interface for communication with a primary automation or control system, which can be used for parameterization, measurement acquisition, remote diagnosis and backup. The modules have an internal digital signal processor, which calculates practical characteristic quantities such as limit values, instantaneous values or peak values, from the measurement signals.
Even time-critical monitoring functions can be implemented in the amplifier itself (e.g. calculating a floating mean of the measurement signals), which relieves the burden on the primary control and the automation system. This powerful signal conditioning is also self-monitoring, thus relieving the burden on the downstream automation systems.
This makes it very easy to implement the distributed structures frequently demanded in automation technology nowadays.
With FDT technology, amplifiers, together with the other field devices, can be parameterized and managed centrally, from a control desk, for example. At the same time, current data can also be read out and visualized in a primary system.
This makes modern asset management possible for an entire system, with centrally managed field device parameterization, measured value visualization and device settings. With an Internet connection, these functions can be made available via a VPN, for example. This makes it very easy to implement remote maintenance concepts with global access.
The DTM for the amplifier that is available with every device, free of charge, is perfectly matched to the device, and supports all the specific amplifier functions.
The ideal solution for printing presses
- In rotary printing presses, digital amplifiers ensure that the paper web is always at the correct tension.
The example of printing press manufacturer Koenig & Bauer impressively demonstrates the many advantages that FDT technology can offer users of a digiCLIP amplifier. A control is integrated into the rotary printing presses of this global company to ensure that the tension of the paper web is always in the optimum range.
This prevents the paper folding or becoming creased, or in the worst case, even tearing. The tension of this paper web is measured at the so-called guide rollers within the printing press. To do this, strain gauges (SG) are fitted to the bearing journals on which the guide roller is mounted. The strain gauges generate a signal when the bearing journal is deformed by the force the paper web transmits to the guide roller.
The connectors of the two full Wheatstone bridges are connected in parallel to a signal amplifier. This allows the strain gauge signals of both the bearing journals to be averaged, and the signal amplifier delivers an output signal that is used for subsequent control.
The servo drivers of the draw rollers on the paper feed and after the printing devices, that transport the paper through the machine, are used as actuators for the control loop.
Koenig & Bauer have completely re-designed the drive and control concept of their rotary printing presses. Instead of distributing control to the drive controllers and the PLC as before, the new control concept uses a so-called Motion Logic Controller (MLC) from Bosch Rexroth.
Sercos is used to communicate with the drives, with the other field devices being connected via Profibus DP. Communication with the control level, which is based on PC technology, takes place via Ethernet.
Type DF30DP digiCLIP amplifiers are used for web tension measurement during re-positioning. They supply an absolute force value which, together with the known geometric variables such as the width of the paper web and the wrap angle of the guide roller, can be directly converted to a web tension force that is related to the width of the paper web.
The big advantage of this technology is that extensive mechanical calibration of the system is not required. As the amplifiers have a Profibus DP interface available, it is very easy to integrate them into the primary control concept of the printing presses. A further advantage of the new system is the ease with which remote maintenance is possible.
Digital amplifiers are again ideally suited to the concept. The primary control can read out the control parameters for paper web tension at any time. This means that the paper web tension control can also be accessed by remote maintenance.
Diverse applications in machinery and plant construction
Of course, FDT technology for digital amplifiers also has advantages in other applications. One such application is its deployment in digital weighing technology. Here, weighing instruments are frequently used in systems to determine material quantities. These can range from small quantities, for dosing in the chemical industry, for example, to vast quantities, like those found in filling operations in silo works. Amplifiers with FDT technology can also be used for load monitoring in container cranes or for monitoring pipes in chemical plants.
The thing that all these applications have in common is that the engineering is made far simpler by using FDT technology. All functions are quick and easy to parameterize with the DTM for the digiCLIP amplifier. Of course, the time saved is reflected in the corresponding cost advantages. But FDT technology does not just have advantages for engineering. Demand-oriented maintenance (asset management) of components can also be implemented.
This leads to increased availability of the corresponding systems, and at the same time reduces maintenance outlay. The DTM is supplied free of charge with all digiCLIP amplifiers, and can also be downloaded from the HBM Website, as required.
digiCLIP
Modular measurement system for industrial environments