Plant Management
Diagram 2. At present, the relay contacts of external hardware must be wired discretely onto the individual loads in order to switch them off. In future this will not be necessary, as the loads ‘talk’ PROFIenergy.
However, with PROFIenergy, the manufacturer has the flexibility to switch off certain parts of the machine rather than the whole unit. This means that during short breaks only the parts which
are quick to reinstate can be switched off, where as the entire unit can be switched off during longer periods of downtime. This means that the manufacturer can maximise the energy savings. PROFIenergy is extremely easy to use. Using
PROFIenergy, a command can be sent from an industrial PLC to the device or machine, instructing it to the length of the break. The device then decides for itself which parts can be
switched off, in order to be ready for operation at the end of the break. It is irrelevant whether this device is an individual component, such as a drive or IO station, or a complex device such as a machine tool or robot. The command structure is always the same (Diagram 3).
Co-ordinated start-up
In order to make the device ready for operation again, the user sends a starting command. This means a co-ordinated startup of the plant is possible, dependent on the application in question. And in order for the user to switch on devices with
different start-up times in a coordinated manner, these devices inform him of their startup time. This allows the user to calculate exactly when the activation command is to be sent. (Diagram 4). In this way, PROFIenergy meets the demand for simple
operation. This is the basis for wider acceptance. It also minimizes the engineering work required. The user only needs to incorporate the two commands
into his program. This enables him to make a hard and fast distinction between the actual control logic for the process and the energy management.
Function blocks
Device and system manufacturers also have the opportunity to support the user by means of corresponding function blocks that, for example, conceal the processing of the communication mechanisms. In order to take into account the user’s requirement for
retrofitting capability and compatibility, these commands are mapped onto existing, tried and tested PROFINET services. In this case, onto records. These acyclic services do not occupy any additional addresses in the process image. In other words, the useful data quantity structure of a PROFINET device is not modified by PROFIenergy. This means that PROFIenergy can be used in existing program libraries and factory standards, such as those that exist in the automobile industry. Likewise, the device manufacturers can upgrade their
existing components to PROFIenergy by using a firmware update. This facilitates a swift implementation – even into existing products. The main benefit for the end user is saving energy and
the costs associated with it. Measurements revealed that even during non-productive periods many plant sections still use between 40 and 60 per cent of the energy that is required during actual production (Diagram 1).
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