Kuhnke Electronics Instruction Manual
Kuhnke Electronics Instruction Manual
Kuhnke Electronics Instruction Manual
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Hardware<br />
3.3.3.1 Power Supply Information<br />
Power to system I/Os and special I/Os<br />
An external source supplies the unit with 24 VDC which a<br />
built-in power supply unit takes to generate the internal<br />
system voltage (5 V) and fed it to the CPU, the device bus<br />
and the fieldbus interfaces.<br />
Please note: always connect the 0V line first and<br />
disconnect it last. You may otherwise experience<br />
equalisation currents go through a V.24 (RS 232)<br />
interface that may be connected. This in turn will cause<br />
the electronic fuse to trip. It will afterwards take about one<br />
minute until the unit has cooled down and is ready to<br />
operate again.<br />
Power to digital I/Os<br />
Power supply to auxiliary push-buttons or other switching<br />
devices that are connected in parallel with the outputs<br />
must also be switched off together with the outputs.<br />
Avoid any reverse feeding of outputs while the power<br />
supply to the outputs is turned off!<br />
This applies if the system is still supplied with power.<br />
Outputs enabled by the user program may be supplied<br />
power via the protective diode of a reversely fed output,<br />
thus overriding the switch-off function of these outputs.<br />
Moreover, the protective diode of the feeding outputs may<br />
yield under high loads and be destroyed.<br />
34 E 700 GB
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