BEKA BA534D, Manual

Page: 23 / 26

23
8.3 Display backlight
The BA534D can be supplied with LED
backlighting to improve display contrast when the
instrument is installed in a poorly illuminated area.
The backlight is electrically segregated from the
measuring circuit and may be powered from any
18 to 30V dc supply.
Reducing the supply below 18V, or fitting a current
limiting resistor in series with the display will
reduce the display brilliance.
Fig 12 shows how the backlight may be powered
from the instrument supply.
Fig 12 Display backlight
8.4 Pulse output
The BA534D may be supplied with an opto-
isolated solid state pulse output. The output is a
polarised current sink that closes for a
programmable duration each time the least
significant digit of the BA534D display changes. A
programmable divider enables the pulse output
frequency to be reduced by 10, 100, 1,000 or
10,000. See Fig 13.
The output pulse is not synchronous with the
BA534D pulse input. The maximum output pulse
frequency is determined by the programmed pulse
width.
Max frequency = _______1_______ Hz
2 x (pulse duration)
If the instrument power supply fails or is
disconnected, any untransmitted output pulses will
be lost.
The output characteristics are:
Ron = 60
Ω
+ 3V
Roff = 1M
I = 10mA max
Fig 13 Pulse output menu
Fig 14 shows a typical application in which the
pulse output is powered from the BA534D supply.
Fig 14 Typical pulse output application