Operation
Getting Started
Connect the VP-TX-120-SS Sensor Transmitter as follows:
4 - 20 mA Output
+V (24 VDC) to TB1, mA Signal Output to TB 2, Common to TB 3.
RS485 (Modbus RTU Protocol)
Data A to TB 8,11 Data B to TB 9 12, Common to TB 7, 10
NOTE: The Analog Output and RS485 are independent of each other and can be used at the same time.
For RS485 operation, the RJ45 Jack can also be used, the pinout is shown in the block diagram above.
Relay Output
NO TB 5 and 6, NC TB 5 and 4
Power On : There is a 120 Second Power On Timer to allow the sensor to stabilize. If the sensor is cold, the sensor should be
allowed to stabilize for a minimum of 24 hours before performing any calibration. During the 120 Second Power On cycle, the LCD will display:
Start Up Display
Warm Up
In xx
where xx is the number in seconds to full operation
There are 6 Main Display Screens. The different screens are accessed with the UP or DOWN Pushbuttons
Pushbutton Operation : There are three pushbuttons, UP, ENTER and DOWN. The basic operation is UP or DOWN to select the display,
ENTER to start or exit a function.
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Normal Operation LCD Screens Examples shown are for a NH3 (Ammonia) Sensor
Screen Number
Screen Display
Description
1. Default Display (after the power on warm up has expired)
0 %LEL
CH4
Default Display, shows the current gas value and units
2. Fault Display
SENSOR
FAULT
If the sensor is disconnected or in fault condition
3. Local Temperature Display
T Local
24.2 C
The temperature sensor is located on the bottom of the PCB ( Near TB 12)
4. Humidity Display
RH
40 %RH
Note: If there is no %RH sensor connected, this display is not shown
5. Software Version Display
TX120-NP
Ver 1.1
Product Model and Software Version
6. Calibration and Programming Menus
Setup
Enter
Programming Entry point, Press ENTER to start
Note: During normal operation or programming operation, if a push button is not activated within 120 seconds, the lcd returns to the default display as shown above in point 1.
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Programming and Calibration
Password Entry
Select the Program Entry Screen
Setup
Enter
Press Enter
Select the Password Enter Display
Password
Enter
Press Enter to access the calibration menus
OR Select the Password Exit Display to return to the main displays
Password
Exit
Press Enter to Exit and return to the main displays
Enter the Password
0000
^
The Default Password is 1020 and is hard coded into the device. The password is used to prevent a casual user from accessing the calibration and programming menus
NOTE: To enter a value, each digit is individually programmed by using the UP or DOWN buttons to select a value. Once the desired digit is programmed, press the ENTER Key to select the next digit. After the final digit is programmed, press the ENTER key to accept the programming. (This method is typical for most programming functions.)
Once the correct password is entered and the screen advances to the first program menu (Zero Calibration), the "P" LED will be lit until the user exits the programming manus.
1000
^
0000
^
0020
^
0000
^
Setup, Calibration and Programming Menus
Setup
Menus
Press the UP button for the first Menu Or DOWN button to go in reverse order
Zero Calibration
Zero Calibration
xx
Zero Cal
where xx is the reading in %LEL
NOTE: Before entering the zero calibration, flow 0 gas or fresh air on the sensor to ensure a proper zero gas calibration.
The "Z" LED will be lit during the ZERO calibration.
Press Enter
0
U EN D
where U = UP, EN = ENTER, D = DOWN Push Buttons
Adjust the reading with the UP and DOWN push buttons to read 0. Press the ENTER button to exit and save the the calibraion.
Zero Calibration is Complete
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Span Calibration
Span Calibration
xx
Span Cal
where xx is a number representing the current gas reading
NOTE: The user should apply the calibration gas to the sensor for an appropriate time (minimum 2 minutes) to allow the sensor to stabilize to the calibration gas value before entering the span calibration
The "S" LED will be lit during the SPAN calibration.
Press Enter
0
U EN D
where U = UP, EN = ENTER, D = DOWN Push Buttons
Use the UP and DOWN push buttons to make the reading equal to the Span Calibration Gas applied.
Sensor Type
Selecting a New Sensor, Type, Ranges and Setpoints
CH4
Gas Type
where XXX is current Gas Sensor Type
Press Enter
CH4
%LEL
Displays the units of measure for the Gas Type
Sensor Range
Selecting a New Sensor Range
xxx
Range
where XXX is current Gas Sensor Range
Press ENTER to program a new Gas Sensor Range
NOTE: The Analog 4 - 20 mA Output tracks this value
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Status LED Set Points
Status LED Low Set Point
xxx
SP Low
where XXX is current Set Point
Press ENTER to program a new Set Point
Status LED Mid Set Point
xxx
SP Mid
where XXX is current Set Point
Press ENTER to program a new Set Point
Status LED High Set Point
xxx
SP High
where XXX is current Set Point
Press ENTER to program a new Set Point
Status LED Set Point Differential
xxx
SP Diff
where XXX is current Set Point
Press ENTER to program a new Set Point
Relay ON / OFF Delays
Set the Relay ON delay in Seconds
xx
On Dely
where XX is current On Delay in Seconds (Default is 1 Second)
Press ENTER to program a new Setting
Set the Relay OFF delay in Seconds
xx
Off Dely
where XX is current Off Delay in Seconds (Default is 1 Second)
Press ENTER to program a new Setting
Audible
Enable Audible ON or OFF
Audible
xx
where XX is current setting On or Off
Press ENTER to program a new Setting
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Modbus ID
Program a new MODBUS ID Number
Modbus
ID = 10
The Default Setting is ID = 10
Press ENTER to program a new ID ( 1 thru 253 )
RS485 Baud Rate
Program a new Baud Rate Number
xx
Baud
where XX is current Baud Rate Setting
Press ENTER to program a new Setting ( 9600 OR 19200 Baud)
Calibrate 4 - 20 mA Output
4 mA Calibration
4 mA
Cal
Press ENTER to Calibrate the 4 mA Setting
Update 4 mA Calibration
Cal 4 mA
U EN D
Measure the mA Output
Press the UP or DOWN push buttons to give a 4.00 mA Output
Press ENTER to Exit
20 mA Calibration
20 mA
Cal
Press ENTER to Calibrate the 20 mA Setting
Update 4 mA Calibration
Cal 20 mA
U EN D
Measure the mA Output
Press the UP or DOWN push buttons to give a 20.00 mA Output
Press ENTER to Exit
Manual 4 - 20 mA Output
Test Calibration
Manual
Output
Press ENTER to set a 0 to 20 mA Output
Used for testing purposes. The analog output can be set to a pre-determined value for system testing. Once the Menu is exited, the analog output reverts back to normal operation and tracks the gas value.
Exit Programming and Calibration Menus
Exit
Setup
Exit
Press ENTER to Exit
End of Programming Menus
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Temperature Sensor Calibration
There is no calibration needed for the Temperature Sensor. The VP-TX120-CH4 has been programmed with a Steinhart equation for calculating the temperature value based on the Thermistor reading and Thermistor Beta value (B 0/50 = 3380). A 1% Thermistor is used and typically the accuracy is +/- 1 °C over the operating range of -20 to + 60 °C.
Humidity Sensor Calibration
There is no calibration required for the humidity sensor. The VP-TX120-CH4 has been programmed with the transfer function supplied with the Honeywell HIH series sensor. After Temperature compensation, the Humidity sensor is guaranteed to have an accuracy of +/- 3% RH from 5 to 95 % RH range, non-condensing.
Status LED
The Status LED shows the following:
GREEN = OK, RED (Flashing) = Sensor Fault, AMBER = Low Alarm, AMBER (Flashing) = Mid Alarm, RED = High Alarm
Audible
The Audible can be programmed either ON or OFF and is fixed to the HIGH alarm setting. If the Audible is enabled and ON, it can be silenced by pressing any pushbutton.
The Audible is also used as a pushbutton "Click". This feature is always enabled.
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