an ISO 9001:2008 certified company
Discontinued
Models 294/269
High Resolution, Linearized
Frequency Transmitters
Operational Manual
For Models
269-0XX-XXX
294-0XX-XXX
294-1XX-XXX
Discontinued
Table of Contents
General Description ................................... 3
Specifications .............................................4
Installation (269) ........................................5
Installation (294) .......................................6
High Temperature Operation ...............7-8
Additional technical documents regarding transmitter performance and advanced
operation are available at: http://www.maxmachinery.com/
Max Machinery, Inc. reserves the right to make changes to the product in this instruction manual to improve
performance, reliability, or manufacturability. Contact Max Machinery Inc. for the latest available specifications and
performance data. Although every effort has been made to ensure accuracy of the information in this instruction
manual, Max Machinery Inc assumes no responsibility for inadvertent errors.
294-000-350 Rev 11/09 © 2008-9 Max Machinery, Inc.
2
General Description
Discontinued
The Model 294 and 269 frequency transmitters are designed
to work with Max flow meters to provide extremely precise flow
measurement in a cost effective package. Different options for
electrical connections and temperature ranges cover a wide
range of application environments – from the laboratory to harsh
industrial processes.
This latest generation of transmitters use modern sensor
technology coupled with advanced signal processing to deliver
new levels of performance and reliability. Hall sensors are used to
detect the position of a driven magnet inside a Max flow meter.
Changes in position are tracked by a microprocessor, which
generates an output frequency proportional to the flow rate.
Advanced signal processing provides both fine angular resolution
(0.36 degrees rotation per pulse) and rapid response (output updated every ms).
These transmitters are typically mated to a mechanical flow meter, configured, and calibrated at
the factory as a matched set. This ensures accuracy and allows quick setup in the field. For field
installations where the transmitter has not been setup with a meter at the factory, an optional serial
interface kit provides full access to all configuration options and parameters.
Transmitter Features
High resolution measurement - Configured output resolution of 1 to 1000 pulses per revolution.
Linearization of up to 16 points to fully describe the flow meter’s output curve and achieve the
highest system linearity over the meter’s entire operating range.
Compensation Algorithm - Compensates for variations in Hall sensor and flow meter characteristics to
provide a stable, undamped output frequency that accurately represents the instantaneous flow rate.
Anti-Dither Pulse Buffer - Prevents undesired reverse pulses which can occur at very low flow rates
in the presence of vibration or hydraulic noise. If the meter reverses direction and then resumes
forward rotation, the pulse count will represent only the total forward flow. Reverse flow exceeding
the pulse buffer setting will result in an output frequency proportional to reverse flow rate. The
buffer quantity can be set from 1% to 100% of a revolution.
3
Transmitter Specifications
Discontinued
Supply Voltage 5-26 Vdc
Supply Current 25-30 mA typical
Output (5.0 Volt Supply) No Load 0.00 / 4.80 Volts
(TTL and CMOS compatible) 2.5K Load to Common 0.00 / 4.60 Volts
2.5K Load to +5 Volts 0.25 / 4.80 Volts
Short Circuit Current
Output Impedance 100 Ω
Rise/Fall Time 0.2 μ Sec
Output Update Rate
Min/Max Frequency 0-60 kHz
Resolution 1 - 1000 pulses/rev, Single Phase
1 - 500 pulses/rev, Quadrature
Ambient Temperature Range Transmitter (Storage) –40ºC to 85ºC (–40ºF to 185ºF)
Transmitter (Operation)
Maximum Temperature, Process Fluid
(30ºC Ambient, 5V supply) 294/269-x0x-xxx (Standard Model) 90ºC (195°F)
294/269-x1x-xxx (High Temp Model) 160ºC (320°F)
294/269-x2x-xxx (Ultra High Temp Model) 215ºC (420°F)
(1)
45 mA
(2)
1 ms
(3)
–40ºC to 80ºC (–40ºF to 175ºF)
Anti-dither Range Software selectable from 1 - 100% of 1 revolution.
Default values: 50% Single Phase
2% Quadrature
Signal Filtering Software selectable from 1ms to 250ms time constant
(1) Continuous Short Circuit is not recommended. The output current should not exceed 10 mA
(2) Events are seen as output transitions 1 msec after they occur
(3) Temperature of metered fluid will affect transmitter temperature, see graph
4
Installation - Model 269
Discontinued
Model 269 - Mechanical Installation
Transmitters are installed on the meter at the factory. If a transmitter needs to be replaced in the
field, use the following procedure:
1. Disconnect wiring and remove the two socket cap screws to remove old transmitter.
2. Position alignment key on new transmitter with corresponding notch on the flow meter and drop
into place.
3. Tighten both socket cap screws until snug. Ensure that the transmitter is not crooked, then turn
screws a 1/4 turn. Do not over tighten.
Electrical Connection
This model is wired at the factory. All that is required is to connect the transmitter’s mating cable
into the remainder of the system as follows:
Blue: Case Ground
Black: Common
Brown: Power (+5-26 Vdc)
White: Output Signal
Programming the Transmitter
Contact the factory regarding P/N 294-100-050, user interface software.
5
Installation - Model 294
21
4
3
21
4
5
3
Discontinued
Mechanical Installation
1. Attach transmitter to the threaded magnet shield on top of the flow meter. Hand tighten. (~ 3 ft - lb)
2. If necessary, loosen set screws on the transmitter’s cap and rotate to align cable as desired.
3. Ensure cap is firmly pushed down to seal O-ring. Tighten set screws.
Removal
1. Remove electrical connections
2. Unscrew transmitter, using a wrench if necessary.
Removal note: The transmitter does not need to be removed from the flow meter for any field servicing or adjustments.
Normally, the flow meter and transmitter are shipped back to the factory for calibration or service as a unit. If the
transmitter needs to be removed from the flow meter for installation, be sure to retighten the transmitter snugly in order
to seal the o-ring and to ensure proper sensor alignment.
Moisture Protection
On all models, the housing is designed as a liquid and vapor-tight enclosure. There are o-ring seals
at the lid and base of the housing – these both need to be fully seated. A properly sealed transmitter
will prevent the formation of damaging moisture inside the housing.
Turck connector Model: The connector is sealed to the lid at the factory and is ready for use.
NPT Model: To ensure a moisture-tight seal, apply appropriate sealant to the threads at installation.
1
Transmitter may be wrench tightened up to 15 ft - lb if it will be subject to vibration or loads. This additional torque
causes relative movement between transmitter and meter, so to ensure optimal performance, request that the factory
apply the extra torque before calibration / compensation, or run the compensation program in the field after tightening.
1
Electrical Installation -
Wiring
The electrical connector versions are pre-wired inside the transmitter and ready to accept a mating
cable (available from the factory). The liquid-tight, NPT models need to be wired during installation
as shown in the table below:
Frequency
Single Phase
Case Ground In-lid
Common 1 Black 4
Power 5-26 Vdc 2
Pulse Output 3 White 2
Frequency
Quadrature
Case Ground In-lid
Common 1 Black 4
Power 5-26 Vdc 2
Output Phase A 3 White 2
Output Phase B 4 Grey 5
NPT model
Connector
Terminal #
NPT model
Connector
Terminal #
Mating Cable
Wire Color
Blue
Brown
Mating Cable
Wire Color
Blue
Brown
4-Pin Connector
Pin #
3
1
5-Pin Connector
Pin #
3
1
6
Rotation/Output Indicators
Discontinued
The red/green rotational indicating LED (D2) will be illuminated when the circuit has power. One side
will always be lit. The color will depend on where the meter stops in its rotation. The yellow signal
LED’s illuminate only when the sensor output is “high”.
Note: There are no selections or adjustments to be made on the circuit board. The only method of
altering the setup parameters is through the Serial Interface Program. (see manual)
High temperature operation above 65°C (150°F)
The operating limit of the meter/transmitter is a function of both the ambient and the metered fluid
temperature, as shown in the graph below. Although the electronic components are rated to 80°C
(175°F), additional heat can be conducted from the flow meter into the transmitter housing requiring
a lower ambient temperature limit for high fluid temperatures.
To prolong the life of the transmitter and reduce the risk of component related failures over time,
high ambient temperatures >65°C (150°F) should be avoided if possible. It is a good idea to locate
the transmitter away from hot spots such as steam pipes, ovens and heaters. When working with
elevated fluid temperatures >65°C (150°F), insulating the flow meter is recommended to reduce the
risk of burns, and to reduce the heating of the electronics by convection of hot air off of the meter
(especially for larger meters). The upper temperature limits shown in the curves rely on ambient
convection to remove heat from the transmitter housing, cooling the electronics. For this reason,
if operating near the upper temperature limit, the transmitter should not be insulated. At these
elevated temperatures, the transmitter will be very hot – exercise appropriate caution.
7
Ambient Temperature °CAmbient Temperature °C
Discontinued
Temperature Limits
Model 269 Transmitter Series
8 0 ° C
60
40
20
0 50
80
Standard
model limit
Process Temperature °C
Temperature Limits
Model 294 Transmitter Series
8 0 ° C
60
40
100 150 200 250
170 210
Hi temp
model limit
(24vdc)
Hi temp
model limit
(5vdc)
*Note: Ultra high temp model must be mounted
with transmitter on side of the flow meter
Ultra Hi* temp
model limit
(24vdc)
280265
300° C
Ultra Hi* temp
model limit
(5vdc)
20
0 50
110(24vdc) 125( 5vdc)
100
Standard
model limits
150 200
Process Temperature °C
205
Hi temp
model limit
(5vdc)
*Note: Ultra high temp model must be mounted
with transmitter on side of the flow meter
250
Ultra Hi* temp
model limit
(24vdc)
285240
Ultra Hi* temp
model limit
(5vdc)
300° C
8
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