ABLE BA688CF-P, Инструкция по установке и обслуживанию

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5
3. SYSTEM DESIGN
The BA688CF-P may be connected to any
PROFIBUS PA segment as shown in Fig 2
providing it can provide the additional 25mA
required to operate the BA688CF-P PROFIBUS
display.
Fig 2 FISCO fieldbus system
3.1 External switches
For applications requiring operator inputs to be
made by large industrial push buttons, terminals
S1 to S7 allow up to six external switches to be
connected to the BA688CF-P PROFIBUS display.
When external switches are connected the front
panel push buttons may be operated in parallel or
disabled – see section 5.3.7
Terminals S1 to S7 are not electrically isolated
from the fieldbus terminals, therefore external
switches and wiring must be isolated from earth
and other electrical circuits.
For reliable operation it is recommended that the
coble connecting the Fieldbus Display to external
switches is less than 5m long.
3.2 Alarm outputs
Each alarm output is a galvanically isolated single
pole solid state switch output as shown in Fig 3.
Fig 3 Equivalent circuit of each switch output
The outputs are polarised and current will only flow
in one direction. Odd numbered terminals should
be connected to the positive side of the supply.
Ron = 5

+ 0.7V
Roff = greater than 1M

Note:
Because of the series protection diode,
some test meters may not detect a closed alarm
output
WARNING
These Alarm Outputs should not be used
for critical safety applications such as an
emergency shut down system.
When the BA688CF-P PROFIBUS display is
disconnected from the fieldbus, or the fieldbus is
de-energised all the alarm outputs will open
irrespective of how they have been configured.