Pin functions, Safety various operating modes – Martel Electronics DPM125 User Manual
Page 2
PIN FUNCTIONS
1. DP1
199.9
2. DP2
19.99
Connect to V+ to display required DP.
3. DP3
1.999
4. TEST
Connect to V+ to display segments as illustrated. It should not be operated for more than a few seconds as the d.c. voltage applied
to the LCD may 'burn' the display. This pin is normally at 5V below V+ and is the ground for the digital section of the meter. It can be
used to power external logic up to a maximum of 1mA.
5. V-
Negative power supply connection.
6. V+
Positive power supply connection.
7. IN HI
Positive measuring differential input.
Analogue inputs must be no closer than 1V to either the positive or negative supply.
8. INLO
Negative measuring differential input.
9. COM
The ground for the analogue section of the A/D converter, held actively at 2.8V (nom.) below V+. COM must not be allowed to sink
excessive current (>100 A) by connecting it directly to a higher voltage.
10. RLO
Negative input for reference voltage (can be connected to COM via Link 3).
11. RHI
Positive input for reference voltage (connected via Link 1 to ROH).
12. ROH
Positive output from internal reference.
µ
To comply with the Low Voltage Directive (LVD 93/68/EEC), input voltages to the module’s pins must not exceed 60Vdc. If voltages to the
measuring inputs do exceed 60Vdc, then fit scaling resistors externally to the module. The user must ensure that the incorporation of the
DPM into the user’s equipment conforms to the relevant sections of BS EN 61010 (Safety Requirements for Electrical Equipment for
Measuring, Control and Laboratory Use).
SAFETY
VARIOUS OPERATING MODES
ON-BOARD LINKS: In order to quickly and easily change operating modes for
different applications, the meter has several on-board links. They are designed
to be easily cut (opened) or shorted (soldered).
Do not connect more than one meter to the same power supply if the meters cannot
use the same signal ground. Taking any input beyond the power supply rails will
damage the meter.
Normally
SHORTED
Cut to
OPEN
Normally
OPEN
Solder to
SHORT
Measuring a floating voltage source
of 200mV full scale.
Split supply operation.
Measuring a supply voltage.
(min. 7.5V, max. 14V).
Measuring the ratio of two voltages.
Reading = 1000 V /V
50mV< V <200mV
V <2V .
1
2
2
1
2
Measuring current. Supply MUST
be isolated.
Measuring 4-20mA to read 0-999.
(supply MUST be isolated).
Check Links 2 & 3 are SHORTED.
Check Link 3 is SHORTED.
Check Links 2 & 3 are SHORTED.
Check Link 3 is SHORTED.
Check Links 1 & 4 are OPEN.
Check Link 3 is SHORTED.
10
7
V-
V-
V+
V+
+
+
+
±200mV
0V
1V
min.
+
-
-
-
-
--
-
V
2
±200mV
V
1
6
5
11
REF HI
IN HI
IN HI
IN HI
REF LO
IN LO
IN LO
IN LO
6
6
6
8
8
8
5
5
5
V-
V-
V-
V-
V-
V-
7
7
7
V+
V+
V+
V+
V+
V+
8
R
+
R=0.2
IF.S.R.
IN
HI
IN
LO
IN
HI
IN
LO
V-
V-
V+
V+
SUPPLY
VOLTAGE
8
7
5
6
510K
10K
510K
V-
V+
8
7
5
6
I
IN
6R2
SET
ZERO
100K
5K
9
IN HI
IN LO
COM
I
OUT
V-
V+
14V max
7V min
Specifications liable to change without prior warning
DPM 125
Issue 3
August/1997
M.C.
Applies to DPM 125/2
Martel Electronics, Corp. P.O. Box 770 Londonderry, NH 03053
Toll Free: (800) 821-0023 Phone: (603) 434-1433 Fax: (603) 434-1653