CM-Series
The CM-35XTL is a functional replacement for the CM-35X meter, but requires only a 1 V loop drop to operate, making it especially suitable for current loops that would otherwise exceed their power supply capacity with too many devices connected. Its counterpart, the CM-35XT, is a lower-cost alternative to the CM-35XTL. It has the same pinout as the CM-35XTL but a higher loop drop of 6.5V, making it suitable for applications where fewer devices are in the current signal loop.
The meters feature Display Hold, Display Test and Auto-Polarity indication. The polarity indication may be disabled or reversed by repositioning jumper clips on internal header pins. Another feature of the CM-series meters is the 4 1/2 digit LCD display which provides for a non-active trailing dummy zero or a C/F descriptor. Descriptor indication may be disabled or re-programmed by repositioning jumper clips on internal header pins.
The CM-35XTL & CM-35XT are designed to be easily user scaled and calibrated to almost any conceivable engineering unit, such as temperature, pressure, viscosity or flow rates etc., without requiring component changes.
The CM-Series is shipped in a standard Slim Bezel case. The Slim Bezel case is compatible with the TM, SM, PM, & SP Series of meters. The CM-Series can be ordered in End Mount cases for twin mounting or combinations of multiple center mount cases and two end mount cases for stack mounting.
Input Configuration:....Series connection to 4-20 mA DC
current loop
Loop Excitation:............External
Full Scale Ranges:........Standard meter is adjustable to any scaling
between 1999 to +1999 without component changes
Input Impedance:..........1 volt drop @ 20 mA Maximum Overcurrent:....200 mA continuous A/D Converter:..............12 bit dual slope Accuracy:......................(0.05% of reading + 2 digits) Temperature Coefficient:..100 ppm/ C (typical) Warm Up Time:..............One minute to specified accuracy Conversion Rate:..........3 readings per second Display:..........................0.48" Liquid Crystal Display (LCD)
Other devices can also be added to the loop.
Fully User Scalable
"Display Hold"
Polarity:..........................Automatically displays either "+" or "";
24V External
Loop Supply
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 Supply is Required; as
the unit derives its power from the 4-20 mA current loop signal
Operating Temp.:..........20C to +50C Storage Temperature:........-20 C to +70 C Relative Humidity:............95% (non condensing) Case Dimensions:........Bezel (2.755W x 1.170H) 69.68mmW x 29.72mmH
Depth behind bezel (3.315) 84.2mm Plus (0.685) 17.4mm for connector
Weight:..........................87 gms (3.1 oz)
142 gms (5 oz) when packed
CM-35XT.................3.5 digit LCD, Loop Powered, 4-20mA (1.0.0.0.0)
CM-35XTL........3.5 digit LCD, 1 Volt Drop, Loop Powered, 4-20mA (1.0.0.0.0)
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 CM35XTL interconnects by means of a standard PC board edge connector having two rows of 10 pins each, spaced on 0.156" centers. 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 internal protection has been provided, it is advisable to handle the meter with ground protection.
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 screwdriver 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 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 current 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 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: The functional diagram shows the additional connections for in-circuit display test activation. An external 225 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 display test activation.
CAUTION: The Display Test function is only intended for momentary operation. Continuous application of Display Test will in time damage the display.
562
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)
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.
September 10, 2003 CM-35XTL Data Sheet(X08)
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-35XTL 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 symbols such as 0, C or F. This trailing non-active zero can be used to display engineering units such as 15000 rpm instead of 15.00k rpm as required with 3 1/2 digit displays.
The meter is shipped with the jumpers in the '0' position. To disable all segments, remove all the jumper clips from the descriptor header.
FRONT OF METER
mA (i.e. from 4 to 20 mA), the display will change by 550 x 4 = 2200 counts.
2. Calibrate the ZERO OFFSET Remove the ZERO RANGE jumper clip from the CALIBRATE position and replace it in the NEGATIVE, MID RANGE or POSITIVE position, depending on whether the required meter reading at 4 mA 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 potentiometer (R15) to make the meter display indicate the correct reading (300 in the example).
3. Check the Scaling Apply loop currents of 4 mA and 20 mA. Verify that the meter indicates correctly at both currents. Slight adjustments to the SPAN RANGE and ZERO RANGE potentiometers may be required.
4. Program Decimal Points and/or Trailing Descriptor Refer to the "Decimal Point Selection" section on page 4 for decimal point programming. Refer to the "Descriptor Selection" for descriptor header jumper clip positions.
CALIBRATION OF "REVERSE" SCALINGS "Reverse scalings that require a more positive heading at 4 mA than at
20 mA, such as 100.0 at 4 mA and 0.0 at 20 mA can be accomplished by calibrating the meter to indicate 1000 at 4 mA and 000 at 20 mA and then reversing the display polarity indication. Refer to the "Polarity Display Header" section on this page for polarity reversal.
Texmates individual screw terminal blocks offer a convenient alternative to edge connectors for many applications, allowing complete installation, configuration and calibration without the need for soldering.
Slide each terminal block over the
TB-KIT
included
PCB until the hole aligns. Insert the retaining screw to secure.
Each kit includes: 3 plastic blocks with metal contacts, 4 screws with spade connectors, 1 metal contact and 3 quick disconnects.
The meter is shipped from the factory with all the decimal points on. To turn off unwanted 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). Reconnect by soldering where shown.
The CM-35XTL derives its power from the 4-20mA current loop signal.
They provide the greatest convenience and ease of use 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.
The CM-35XTL functions by measuring the voltage drop caused by the 4-20 mA 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 4 mA, it is usually necessary to Zero Offset the meter reading. This enables zero or some other appropriate value to be displayed at 4 mA, 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 4 mA to 20 mA. 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 20 mA and 30.0 at 4 mA, then the SPAN is (+1900) minus
(300), or 2200
counts. The ZERO
OFFSET is simply
defined here as the displayed counts
at 4 mA. In the example above, the
ZERO OFFSET is
300 counts.
CALIBRATION
One header & potentiometer calibrate the span range (the change in meter reading between 4 mA and 20 mA). The second header & potentiometer calibrate the zero offset (the meter reading at 4 mA). To avoid interaction between the SPAN RANGE and ZERO RANGE potentiometers, the calibration is performed in the following sequence:
1. Calibrate the SPAN Place a jumper clip in the CALIBRATE position on the ZERO RANGE Select Header. This disables the ZERO RANGE potentiometer.
Depending upon the calculated SPAN, place a jumper clip in the appropriate position on the SPAN RANGE header. In the above example, this would be the position marked 1400-3000.
Apply an input of 4 mA to the meter. This input can be derived either from a Current Calibrator (fig. 1), a 5 V DC supply /resistor combination (fig. 2) or from within a current loop, by varying the loop transmitter transducer appropriately. Adjust the SPAN RANGE potentiometer (R2) to make the meter display one quarter of the calculated SPAN. In the previous example the meter would be adjusted to show 2200 4, i.e.
550 counts. Once calibrated, the display changes by 550 counts for a loop current change of 4 mA. Therefore when the input changes by16
Part Number: CN-PUSH/CM
The Slim Bezel Case is supplied as standard. If specified at time of ordering, any combination of Twin Mounting and Multiple Array Cases may be substituted at no additional cost. Extra cases may be ordered separately.
STANDARD SLIM BEZEL CASE
OPTIONAL TWIN MOUNTING OR MULTIPLE ARRAY CASES
0.68"
(17.22mm)
Standard Options for this Model Number
Description
Part Number
(cid:2)BASIC MODEL NUMBER
CM-35XTL.......3.5 digit LCD, 1V Drop, Loop Powered, 4-20mA (cid:2)SPECIAL OPTIONS (Specify Req. Reading) CB-FS35.........Non-Std Scale Changes, 3.5 Digit Meters
(101.6mm)
3.32"
(84mm)
Front Panel Cutout
0.96"
(24.4mm)
2.52"
(64.2mm)
0.304"
(7.72mm)
0.19"
(4.88mm)
2.26"
(57.4mm)
2.76"
(69.75mm)
1.17"
(29.7mm)
0.58"
(14.71mm)
0.95"
(24.23mm)
Special Options and Accessories
Description
Part Number
(cid:2)ACCESSORIES
CN-L10..........PCB Edge Connector, Solder Type, Dual Row 10 Pins CN-PUSH/CM.....CM Series Push-on Screw Terminal Block Connector SL.CASECLR......Slim Bezel Case, Clear Faceplate w/Mtg Hardware CM.CASECLR.....Center Mount Case, Clear Faceplate w/Mtg Hardware EM.CASECLR.....End Mount Case, Clear Faceplate w/Mtg Hardware TB-KIT...........Replacement Terminal Block Connector Kit (3)
For product details visit www.texmate.com
Local Distributor Address
995 Park Center Drive Vista, CA 92081-8397
Tel: 1-760-598-9899 USA 1-800-839-6283 Thats 1-800-TEXMATE Fax: 1-760-598-9828 Email: [email protected] Web: www.texmate.com
September 10, 2003 CM-35XTL Data Sheet(X08)
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.