Texmate, Inc. Tel. (760) 598-9899 • www.texmate.com
Page 2
September 10, 2003 CM-35XTL Data Sheet(X08)
Functional Diagram
Connector Pinouts
Component Layout
COM
1XX.X
1X.XX
COM
1.XXX
TEST
0.48" Display
HI
HOLD
LOW
12 Bit
Dual Slope
A to D
Converter
& Display
Driver
GND
+ 3 V
– 3 V
Input HI
Input LO
Hold
Test
Span Range
Header
Offset
Trim
Descriptor
Header
0.22
µ
F
Span
Pot
1.62
10 to 1500
1400 to 3000
2900 to 4000
10
2.43
2.43
Zero
Pot
– 3 V
+ 3 V
+1.25V
90K9
33K
22K
100K
100K
32K4
20K
31K6
78K7
–1.25V
Negative
Zero Offset
Range Header
Mid Range
Positive
CAL
T
o
Displa
y
48KHz
Clock
Circuit
Power
Supply
Circuit
Factory Preset
Do not adjust.
DP Common
DP Common
Display Test
Hold
1XX•X DP
1X•XX DP
1•XXX DP
Input LO
Input HI
Pins A, 1 and 3 - Decimal Select: Decimal points may be
blanked as required by carefully scraping off the fine tracks link-
ing these pins to Decimal Select Common using a pair of pliers
or a small screwdriver blade. Re-connect either by linking the
appropriate pins on the connector or by solder-bridging the junc-
tions located on the PC board edge fingers.
CAUTION: Do not connect the decimal select pins to any pins
other than Decimal Select Common Pins B & 2. Although the
decimals may become activated if an improper connection is
made to other pins, this will eventually cause permanent damage
to the display.
Pins B and 2 - Decimal Select Common: Common return pins
for decimal point selection (see CAUTION above).
Pins (D, E) & (4, 5) - Current Loop Low Input: The 4-20 mA cur-
rent loop is returned from Pins (D,E) & (4,5). At 4 mA the meter
displays the minimum reading. At 20 mA the meter displays the
maximum reading.
Pins (F, H) & (6, 7) - Current Loop High Return: The 4-20 mA
current loop is applied to Pins (F,H) & (6,7) and returned from
Pins (D,E) & (4,5). If reverse polarity is applied no damage will
occur; however the meter will not operate (this condition should
not be maintained for extended periods).
Pins (J, K) & (8, 9) - Display Hold Input (CMOS compatible): If Pins (J, K)
& (8, 9) are left open, the meter will operate in a free-running
mode. When Pins (J, K) & (8, 9) are connected to Current Loop
High Input Pins (D, E) & (4, 5) the meter will latch up; A/D con-
versions will continue but the display will not be updated until Pins
(J, K) & (8, 9) are released.
Pins L and 10 - Display Test Input: The functional diagram
shows the additional connections for in-circuit display test activa-
tion. An external 225
Ω
resistor is placed in series with the meter
when the test switch is operated. This increases the overall loop
drop to 5.5 V @ 20 mA, which is required for reliable in-circuit dis-
play test activation.
CAUTION: The Display Test function is only intended for momen-
tary operation. Continuous application of Display Test will in time
damage the display.
For most applications where it is not necessary to activate Display
Test or remotely change the selected decimal point, the three
screw terminal blocks supplied with the meter can be used to con-
nect Current Loop High Input, Current Loop Low Return and
Display Hold Input. For other applications, the Texmate CM-
35XTL interconnects by means of a standard PC board edge con-
nector having two rows of 10 pins each, spaced on 0.156" cen-
ters. Connectors are available from Texmate, or from almost any
connector manufacturer.
CAUTION: This meter employs high impedance CMOS circuits
that are susceptible to damage from electrostatic discharge
(ESD), particularly in low-humidity environments. Although inter-
nal protection has been provided, it is advisable to handle the
meter with ground protection.
TEST
1
2
3
4
5
6
7
8
9
10
A
B
C
D
E
F
H
J
K
L
METER REAR WITH PCB EDGE CONNECTOR MOUNTED
(For mounting of screw terminal blocks see rear page)
HOLD
1.XXX
COM
1XX.X
COM
1X.XX
HIGH
LOW
TEST
HOLD
LOW
HIGH
Zero Range
Span Range
Decimal Select - 1
Decimal Select Common - 2
Decimal Select - 3
Current Loop High Input
Current Loop Low Return
Display Hold Input
Display Test Input - 10
A- Decimal Select
B - Decimal Select Common
Display Hold Input
L - Display Test Input
J
K
5
4
6
7
8
9
Current Loop High Input
Current Loop Low Return
D
E
F
H
FINE "SCRAPE OFF" TRACKS
SOLDER JUNCTION
COMPONENT SIDE PINS
SOLDER SIDE PINS
Normal
Disabled
Reversed
Polarity Display Header
This header allows the Polarity indication to
be displayed normally, displayed reversed or
to be disabled completely.
Turn Clockwise to
Increase Reading
To the
Left Front
ZERO Potentiometer (Pot)
The ZERO pot when installed is to the left of the
SPAN pots (as viewed from the back of the
meter). Typically it enables the displayed read-
ing to be offset ±1000 counts.
Turn Clockwise to
Increase Reading
To the
Right Front
SPAN Potentiometer (Pot)
The 15 turn SPAN pot is always on the right side
(as viewed from the front of the meter). Typical
adjustment is 20% of the input signal range.
Signal Conditioning Component
POLARITY DISPLAY HEADER
DESCRIPTOR HEADER
SPAN & ZERO RANGE
SELECT HEADER
ZERO RANGE
R15
R2
ZERO RANGE
SPAN RANGE
562
1.XXX
COM
1X.XX
TEST
LOW
HIGH
HOLD
SPAN RANGE
ZERO RANGE
10 - 1500
1400 - 3000
2900 - 4000
CALIBRATE
NEGATIVE
MID RANGE
POSITIVE
POWER SUPPLY
These 2 components
are used to null the
op-amp offset. They
are set at the factory
and should not be
adjusted by the user.
