BECKHOFF DK9222-0810-0040 - Manual (Page 2)

I/O
I/O, Building Automation
Application Note DK9222-0810-0040
Local override operation
Local override operation enables the direct intervention in the building control system. Via this operating level important
system components can be controlled manually in order to maintain important functions, if the substation is not available, has
failed or is faulty. The operating elements at this level act directly without regard to the automation device.
Local override operation can be realized conventionally with switches and buttons, although it is important to ensure that all
elements are supplied via an independent power supply. To avoid manipulations, access to the local override operation control
elements must be secured, for example through integration in the control cabinet.
If a manual/local operating level or local override operating level is used, all safety functions should be triggered externally.
The local operation system must not be used for safety shutdown. The local override operations are executed directly in
accordance with ISO 16 484-2, section 3.110, without protection or interlock, so that the operator has full responsibility for all
interventions.
2. System-compliant interfaces for field devices and system components, independent of
the central unit
The Beckhoff product range includes the following Bus Terminals for full system integration of manual intervention within
the building control system. The manual operating terminals are system-compliant interfaces for field devices and system
components, which operate independent of the central unit:
KM1644 | 4-channel manual operation
KM2614 | 4-channel relay module, 230 V AC, 16 A, potential-free changeover contacts, with manual operation
KM2652 | 2-channel relay module, manual/automatic operation 6 A, 230 V AC
KM4602 | 2-channel analog output terminal 0…10 V, manual/automatic operation
The four switches and four LEDs in the front panel of the KM1644 are available as digital inputs or outputs in the control
system and they enable the direct input and display of process parameters at the terminal. The combination of four digital
inputs and outputs in a 24 mm terminal block reduces to a minimum the space requirement in the control cabinet as well as
the number of operating elements that have to be installed in the control cabinet door. The avoidance of additional external
operating elements at the door also reduces the personnel requirements, material use and possible error sources (incorrect
wiring).
Consumers from different rating classes can be connected directly to the KM2614 and KM2652 relay module terminals so that
they can be controlled via the changeover contact either by the controller or manually. The KM2614 enables manual control
of four high-power consumers with a current consumption of up to 16 A at 230 V AC. The KM2652 can be used to switch two
New Automation Technology Beckhoff 2
For application notes see disclaimer on the last page