5. Connector CN1
Pin1
IN HI
Positive measuring input
Pin2
IN LO
Negative measuring input
Pin3
VDD
Module DC positive 5 V or +9 V
Pin4
VSS
Module DC negative supply 0 V
Pin5
COMMON
Analog common input
Pin6
BL+
Backlight: connect to +5 V or with external resistor for
+9 V supply.
DPM961: 120 Ω, 0.5 W;
DPM962: 82 Ω, 0.5 W
Pin7
HOLD
Connect to VDD to freeze display
Pin8
REF HI
Positive reference voltage input
Pin9
ON
(Selected) Connect to decimal point inputs
Pin10
OFF
(Not Selected) Connect to all unused decimal point
inputs
Pin11
BL-
Backlight negative supply. Note: connect directly to
0 V not to pin 4
Pin12
DP3
Decimal point 1.999
Pin13
DP2
Decimal point 19.99
Pin14
DP1
Decimal point 199.9
6. Note
Any signal cables connected to this device must not
exceed 30 metres in length. If signal cables are installed
that are routed outside the building, it will be necessary to
install additional surge protection devices.
7. Analogue Inputs and Internal Reference
Voltage
IN HI, IN LO and REF HI are all differential inputs. They
respond to the voltage across them and not to the voltage
with respect to the power supply. The only exception to
this is in 5V mode where the analogue common and VSS
have been connected together. There is a limit to the
voltage which can be measured using a differential input
and this is known as the common mode range.
The internal reference voltage (REF HI) is set by the
potentiometer VR1. The voltage is factory set at 100.0 mV
but may be trimmed to suit individual applications, e.g. to
compensate for the inaccuracy of external resistors when
using scaling configurations.
8. Power Supply Selection
The modules can be operated with 5 or 9 V DC supply
voltage. In 5V operation no separation of measuring and
supply voltage is necessary. In 5V operation, however, the
low battery function must be disabled. In 9V operation, it
may be enabled or disabled. The desired operating mode
is activated by open or closed LK solder bridges on the
printed circuit board of the module.
9. Links and Mode Connections
5-Volt-Mode:
LK5 Open
LK6 and 7 Shorted
9-Volt-Mode:
LK5 Shorted
LK6 Open
Links ANALOGUE COMMON to IN LO:
DPM961: Connect CN1 pins 2–5
DPM962: Solder LK1
Links ANALOGUE COMMON to VSS:
DPM961: Connect CN1 pins 4–5
DPM962: Solder LK2
Links REF HI to VR1 (remove link if using external
reference voltage circuit):
LK4 Shorted
Links REF LO to ANALOGUE COMMON:
LKC Shorted
Links REF LO to IN HI:
LKH Shorted
Disables low battery function. Always disable for 5V
operation:
LK7 Shorted
TEST LINK. Forces display to 1888. Do not use for
more than 2 seconds or damage to the display may
occur:
Briefly bridge LKT
10.Configuration
The instruments are configured for the respective
application circuit by setting LK solder bridges and pin
connections on pin header CN1. The measuring range is
configured by attaching external resistors. With the
DPM962, the resistors can also be soldered internally to
positions RA and RB. A 0 Ω SMD resistor is attached for
RA, which must be removed before the THT resistors can
be soldered.
0.1% resistors are required to maintain an accuracy of
0.1%. This may be relaxed if an accuracy less than this is
required.
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Application Circuits (page 14)
