3 1/2 DIGIT with 0.48 LCD
The CM-35XT is specially designed to simplify in stal la tion, cali bra tion and scaling. Deriving its operating power from the current loop, this meter require no external power supply. The CM-35XT is a functional replacement for the now obsoleted CM-35X meter.
The meter feature Display Hold, Display Test and AutoPolarity Indication. The polarity indication may be dis abled or re versed by repositioning jumper clips on internal header pins. Another fea ture of the meters is the 41/2 digit LCD display which provides for a non-active trailing dummy zero or a C/F de scrip tor. De scrip tor indication may be dis abled or re-programmed by re po si tion ing jumper clips on internal header pins.
Other devices can also be added to the loop.
Fully User Scalable
24V External
Loop Supply
Input Configuration:............. Series connection to 4-20mA DC
current loop
Full Scale Ranges:............... Standard meter is ad just able to any
scal ing between -1999 to +1999 or
-19990 to +19990 with the dummy zero
enabled
Input Impedance:.................. 5.1 Volts drop, plus 70.8
(equivalent to 6.5V Max i mum @ 20mA)
Maximum Overcurrent:........ 200mA continuous
A/D Converter:...................... 12 bit dual slope
Accuracy:.............................. (0.05% of reading + 2 dig its)
Maximum Resolution:.......... 1999 counts
Gain Temp. Coefficient:....... 0.2 counts/ C typical
Zero Temp. Coefficient:...... 0.15 counts/ C typical
Conversion Rate:.................. 3 readings per second
Display:.................................. 0.48" Liquid Crystal Dis play (LCD)
Descriptors:.......................... Header programmable trailing dummy zero, C or F
Polarity:................................. Automatically displays either "+"or "-";
header programmable polarity disable
and reversal
Decimal Selection:............... User programmable to three positions
Over-range Indication:......... When input exceeds full scale on any
range being used, most significant "1"
digit and polarity symbol are displayed
with all other digits blank.
Power Supply:.......................NO SEPARATE POWER SUP PLY IS
REQUIRED; as the unit derives its pow er
from the 4-20mA current loop signal
Operating Temperature:....... -20 C to +50 C
Storage Temperature:.......... -20 C to +70 C
Relative Humidity:................ 95% (non condensing)
Case Dimensions:................ Bezel 2.752 x 1.165 (69.9 x 29.6mm)
Depth behind Bezel 3.33(84.5mm)
plus 0.662 (16.82mm) for connector
Weight:.................................. 143 gms (5 oz) when packed
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CM-35XT
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 connect Current Loop High Input, Current Loop Low Return and Display Hold Input. For other applications, the Texmate CM-35XT in ter con nects by means of a stan dard PC board edge connector having two rows of 10 pins each, spaced on 0.156" centers. Con nec tors are available from Texmate, or from almost any connector man u fac tur er.
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 Return: The 4-20mA current loop is returned from Pins (D, E) & (4, 5). At 4mA the meter displays the minimum reading. At 20mA the meter displays the maximum reading.
Pins (F, H) & (6, 7) - Current Loop High Input: The 4-20mA 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 con di tion should not be maintained for extended periods).
Pins (J, K) & (8, 9) - Display Hold Input (CMOS com pat ible):
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 conversions will continue but the display will not be updated until Pins (J, K) & (8, 9) are released.
Pins L and 10 - Display Test Input: All numeric display segments will operate when Pins L and 10 are connected to Current Loop High Input Pins (D, E) & (4, 5).
Note: Because of the additional current drawn by the circuit in display test mode, 20mA loop current is required for reliable in-circuit display test activation.
CAUTION: The Display Test function is only intended for mo men tary operation. Continuous application of Display Test will, in time, damage the LCD display.
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 reading to be offset 1000 counts.
SPAN Potentiometer (Pot)
Pins A, 1 and 3 - Decimal Select: Decimal points may be blanked as required by carefully scraping off the fine tracks linking these pins to Decimal Select Common using a pair of pliers or a small screw driver blade. Re-connect either by linking the appropriate pins on the connector or by solder-bridging the junctions 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 im proper connection is made to other pins, this will even tu ally cause permanent damage to the LCD display.
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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.
Polarity Display Header
This header allows the Polarity indication to be displayed normally, displayed reversed or to be disabled completely.
Power Supply
The CN-35XT derives its pow er from the 4-20mA current loop signal.
SPAN ADJUST Header
Any input Signal Span can then be scaled down to provide a required Digital Display span from 19999 (40000 counts) to 0001 (one count).
The CM-35XT is designed with a 3 1/2 digit A/D converter and a 4 1/2 digit display. The right-most digit can be enabled to display different sym bols such as 0, C or F. This trailing non-active zero can be used to display en gi neer ing units such as 15000 rpm in stead of 15.00k rpm as re quired with 3 1/2 digit dis plays.
The meter is shipped with the jump ers in the '0' po si tion. To dis able all seg ments, remove all the jumper clips from the de scrip tor header.
FRONT OF METER
Calibration Procedure
The CM-35XT functions by measuring the voltage drop caused by the 4-20mA signal loop current flowing through a sensing resistor located inside the meter. The voltage sensed is scaled by an adjustable potential divider network and converted to a digital reading in counts, shown by the LCD display.Because the loop current does not go down below 4mA, it is usually necessary to Zero Offset the meter reading. This enables zero or some other appropriate value to be displayed at 4mA, even though the voltage across the sensing resistor is not zero. The Zero Offset may be disabled by putting the ZERO RANGE jumper clip into the CALIBRATE position.
DEFINITION OF SPAN AND ZERO OFFSET The SPAN is defined here as the total change in counts on the display when the signal loop current varies from 4mA to 20mA. Note that decimal points and/or non-active trailing zero are descriptors, and so are excluded from the calculation. Example: If the required readings are +190.0 at 20mA and -30.0 at 4mA, then the SPAN is (+1900) minus (-300), or 2200 counts. The ZERO
is simply OFFSET
defined here as the dis played counts at 4mA. In the example above, the ZERO -300 OFFSET
counts.
change of 4mA. Therefore when the input changes by16mA (i.e. from 4 to 20mA), the display will change by 550 x 4 = 2200 counts.
2. Calibrate the ZERO OFFSET Remove the ZERO RANGE jumper clip from the CALI BRATE position and replace it in the NEGATIVE, MID RANGE or POSITIVE position, depending on whether the required meter reading at 4mA is a large negative, close to zero, or a large positive reading. In the previous example, place the jumper clip in the MID RANGE position. Adjust the ZERO RANGE po ten ti ome ter (R15) to make the meter dis play indicate the correct reading (-300 in the example).
3. Check the Scaling Apply loop currents of 4mA and 20mA. Verify that the meter indicates correctly at both currents. Slight adjustments to the SPAN RANGE and ZERO RANGE po ten ti ome ters may be re quired.
4. Program Decimal Points and/or Trailing De scrip tor Refer to the Decimal Point Selection section on page 4 for decimal point programming. Refer to the Descriptor Se lec tion section alongside for de scrip tor header jumper clip positions.
CALIBRATION OF REVERSE SCALINGS Reverse scalings that require a more positive reading at 4mA than at 20mA, such as 100.0 at 4mA and 0.0 at 20mA can be accomplished by calibrating the meter to indicate -1000 at 4mA & 000 at 20mA and then reversing the display polarity indication. Refer to the Polarity Display Header section on this page for polarity reversal.
TB-Kit Screw Connectors
*Not Included
Texmates individual screw ter mi nal blocks offer a convenient al ter na tive to edge connectors for many ap pli ca tions, allowing com plete in stal la tion, con figu ra tion and calibration with out the need for soldering.
Slide each terminal block over the PCB until the hole aligns.
Insert the re tain ing screw to secure.
Each kit includes: 3 plastic blocks with metal contacts, 4 screws with spade connectors, 1 metal contact and 3 quick disconnects.
Part Number: TB-KIT
The meter is shipped from the factory with all the decimal points on. To turn off un wanted decimals, use a pair of long-nosed pliers to scrape of the fine tracks connecting decimals to decimal select common (alternatively, use a scalpel or small screwdriver). Re con nect by soldering where shown.
Push-On Screw Terminals
Texmates exclusive optional Push-On Connectors combine an edge card connector and a 10 position screw terminal block. Push-On Connectors are ordered preconfigured for each specific power supply voltage and each optional power supply available for the CM-Series.
Part Number: CN-PUSH/CM
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PANEL CUTOUT
FRONT VIEW
SIDE VIEW
TOP VIEW
option metal
screw mounting clip
When extra panel mounting tightness is required, optional Screw Mounting Clips can be purchased seperately and attach to the sliding mounting side clips
Standard Options for this Model Number
Part Number
4BASIC MODEL NUMBER
CM-35XT....... 3.5 digit LCD, Loop Powered, 4-20mA
Description
Description
Special Options and Accessories Part Number
4SPECIAL OPTIONS (Specify Req. Reading) ZRS-CM...... Non-Std Scale Changes, 3.5 Digit Meters 4ACCESSORIES
CN-L10....... PCB Edge Connector, Solder Type, Dual Row 10 Pins CN-PUSH/CM.. CM Series Push-on Screw Terminal Block Connector SL.CASERED.. Slim Bezel Case, Red Faceplate w/Mtg Hrdwre TB-KIT........ Terminal Block Connector Kit (3)
1934 Kellogg Ave., Carlsbad, CA 92008 Tel: 1-760-598-9899 1-800-TEXMATE Fax: 1-760-598-9828 Email: [email protected]
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Texmate is an American manufacturer of high durability industrial grade panel meters, bar graphs, and transducers. Texmate's meters are frequently equipped with relays and various signal outputs for industrial automation applications and are known for their extremely long service life.