BEKA BA454D, Manual

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4.4 External switches
For applications requiring the batch controller
to be operated via large industrial push-
buttons, four external switches may be
connected as shown in Fig 2. Each external
switch has a dedicated operating and
configuration function.
Switch
number
Switch function when
Operating Configuring
S1 Start Down
S2 Stop Up
S3 Reset P
S4 Menu E
Section 3.6 describes the use of external
switches in the hazardous area, but they may
also be located in the safe area.
A certified intrinsically safe relay or a galvanic
isolator with a switch contact output is required
to transfer the switch contact from the safe to
the hazardous area. The combined permitted
input safety parameters for batch controller
terminals S1 to S7 are zero, therefore Zener
barriers can not be used.
Fig 8 shows how external Stop buttons may be
located in the safe and hazardous areas.
Fig 8 Stop buttons in hazardous & safe areas
4.5 Inhibit link
Linking terminals 18 and 20 together inhibits
the batch controller input. If linked during a
batch, dispensing will continue but the batched
total will not be incremented, or decremented if
counting down. These terminals may only be
connected to a hazardous area mechanically
operated switch having IP20 protection and
able to withstand an ac test voltage of 500V to
earth for one minute. See section 3.7.
4.6 Security link
Access to the configuration menus is only
available when terminals 18 & 19 are linked
together – see section 6.1. These terminals
may only be lined together at the instrument, or
connected to a hazardous area mechanically
operated switch having IP20 protection and
able to withstand an ac test voltage of 500V to
earth for one minute. See section 3.7.
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