TELEDYNE HASTINGS INSTRUMENTS INSTRUCTION MANUAL MODEL 2002 VACUUM GAUGE ISO 9001 C E R T I F I E D
Manual Print History The print history shown below lists the printing dates of all revisions and addenda created for this manual. The revision level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released between revisions, contain important change information that the user should incorporate immediately into the manual. Addenda are numbered sequentially.
Table of Contents 1. GENERAL INFORMATION......................................................................................................................................... 4 1.1. 1.2. 1.3. 1.4. 2. FEATURES ................................................................................................................................................................. 4 MODEL 2002 SENSORS...................................................................................................................
1. General Information The Model 2002 is a wide range vacuum measuring instrument consisting of a digital microprocessor-based display unit, a miniature, rugged, thin film based sensing element that measures from below 1x10-4 up to 100 Torr, a piezoresistive sensor that measures from 1 to 1000 Torr, EEPROM (Electrically Erasable/Programmable Read Only Memory), and an interconnecting cable. Together, these components provide accurate vacuum measurement over 7 decades of vacuum from 1x10-4 to 1000 Torr.
board is also available. The Model 2002 instrument accepts an external TTL level "Remote Zero" to zero the instrument when another instrument (e.g. an ion gauge) indicates that the pressure is less than 1x10-5 Torr. The standard analog output is linear per decade directly corresponding to the control unit’s display. The Model 2002 comes calibrated for nitrogen. Conversion factors for other gases are selectable by the user (see section 3.5).
2. Installation This section is designed to assist in getting a new pressure gauge into operation as quickly and easily as possible. Please read the following instructions thoroughly before installing the instrument. 2.1. Receiving Inspection Carefully unpack the Hastings Model 2002 Instrument (part # HPM-2002), transducer (part #HPM-2002s) and cable (part # CB 2002). Inspect all items for any obvious signs of damage due to shipment.
2.4. Control Unit Installation • • • • • • Environment: Indoor use Altitude up to 2000 meters Operating temperature range from 50 to 400C Maximum relative humidity: 80% for temperatures up to 310C decreasing linearly to 50% relative humidity at 400C Installation category II Panel Mount Instructions: The control unit can be panel mounted. See detail on page 43. The dimensions of the hole on the panel are 3.62" x 3.62"(92.8mm x 92.8 mm).
3. Front Panel Operation 3.1. Overall Functional Description The front panel of the control unit is shown in Figure 3.1. The four circular blue buttons are used for the selection of display readout and the input of data. The green data field displays the data as determined by mode selection. The MODE switch toggles the control unit in a clockwise fashion among the six modes of operation: RUN Normal operation, pressure is displayed in scientific notation.
Scientific Notation The Model 2002 measures pressure that spans more than seven decades. In order to easily display these readings, Hastings Instruments has employed scientific notation. In scientific notation, the mantissa (the fixed point part) is multiplied by some power of 10 (given by the exponent). Powers of 10 103 = 1000 10-1 = 0.1 102 = 100 10-2 = 0.01 101 = 10 10-3 = 0.001 100 = 1 10-4 = 0.0001 7.60 x 10+2 Torr { As an example: Mantissa exponent "7.
This will not correct the calibration if the tube has become contaminated or damaged. This reset will not affect the gas selection, units or setpoints. Also see unit’s mode for default calibration restoration. 3.3. High and Low Set Point Modes The Model 2002 provides TTL outputs for process control. The I/O cable is attached via a 9-pin sub-D connector to the rear panel of the control unit. The pinout is shown in Figure 4.2.
An important point to be noted is the fact that after the adjustment, the new calibration coefficient is only in temporary memory. If the instrument were unplugged at this point, it would revert back to the original displayed value upon restarting. Place the Model 2002 back in the RUN mode to store all of the current calibration coefficients in permanent memory. To perform a full calibration on the Model 2002 system, first use the Zero Coefficient Adjustment Procedure.
3. Place the instrument in the CAL mode, then simultaneously press the UP and DOWN switches to bypass the interlock. The CAL light will start to flash indicating that the calibration mode has been activated. 4. Press the ZERO switch once if below 6x10-5 Torr otherwise use the UP and DOWN switch to adjust the display of the Model 2002 to match the pressure indicated by the reference.
TABLE 1 Gas Mode Gas Displayed Number 0.0………………………..Nitrogen 0.1…………………...……..Argon 0.2…………………...…….Helium 0.3………………...…Water Vapor 0.4………………....……..Custom light will now flash. Use the UP and DOWN switches to individually select the desired code. Return the Model 2002 to the RUN mode. Note: Factory calibration is performed using nitrogen only. Displayed pressure measurements using other gases are based on established gas thermal conductivity data. 3.6.
4. Rear Panel Description A schematic of the rear panel of the Model 2002 control unit is shown in Figure 4.2 ( Rear Panel Figure). The transducer is connected to the control unit via an female 9-pin “D” connector on the rear panel. An I/O cable can be connected via a male 9-pin “D” connector on the rear panel. The I/O cable provides an analog output signal, a remote zero input capability, high and low alarm TTL outputs, and a + 5 VDC Power Supply Output.
If the analog output voltage is being used in a data acquisition system, the following formulas can be used to calculate pressure. EXP=INT (2*V)-6 MANT=1+18*V-9*(EXP+6) Pressure (Torr)=Mant x 10exp Therefore, Note that the INT function simply returns to the first digit in a number. Examples: INT (2.56) = 2 INT (9.87) = 9 --------------------------------------------------------------------------------------------------------------------- Voltage to pressure conversion example: Given V = 2.
4.3. TTL Outputs TTL outputs are provided for process control. High and Low set points are entered on the front panel (see Section 3.4) and TTL signals are generated on the I/O cable in the following manner: 1. When the pressure as indicated by the Model 2002 is above the High set point, the High signal line (pin #3) will be set to a TTL high level (+5 VDC). When the indicated pressure is below the High set point, the High signal line (pin#3) will be set to a TTL low level (+0 VDC). 2.
Analog 0-10V OPTION BOARD CONNECTOR Pin# Connection 1 Analog Out 1 (1024 Torr) High 2 Analog Out 1 (1024 Torr) Shield 3 Analog Out 1 (1024 Torr) Low 4 5 6 7 Analog Out 2 (1000 mTorr) Low 8 Analog Out 2 (1000 mTorr) High 9 Analog Out 2 (1000 mTorr) Shield 4-20mA OPTION BOARD CONNECTOR Pin# Connection 1 I-Loop Out (+) 1024 Torr 3 I-Loop In (-) 1024 Torr 8 7 I-Loop Out (+) 1000 mTorr I-Loop In (-) 1000 mTorr SENSOR CONNECTOR Pin# Connection 1 Sensor 2 Bridge (sense) 3 Bridge-Power 4 Reference 5 Common 6 Comm
5. Theory of Operation The Model 2002 transducer is comprised of two very different sensors which provide a span of measurement extending from 1000 Torr down to less than 1x10-4 Torr. The piezoresistive device is a direct force sensor which provides pressure indication from 1000 Torr down to less than 1 Torr. The thin film Pirani device is a thermal conductivity sensor that provides pressure indication from 100 Torr down to less than 1x10-4 Torr.
To insure temperature invariance, dVo ⎛ SdV VdS ⎞ = P⎜ + ⎟ dT dT ⎠ ⎝ dT dVo = 0 Therefore dT 1 dV ⎛ 1 dS ⎞ = −⎜ + ⎟ V dT ⎝ S dT ⎠ This requires for any change in sensitivity to be countered by an equal but opposite change in applied voltage. The temperature compensation is a network of temperature dependent resistive components and fixed temperature compensation current source compensation, TCR = -TCS.
5.2. Pirani Sensor Figure 5.3a shows a thin film Pt resistive element on a one micron thick Si3N4 continuous membrane surrounded by a thin film Pt reference resistor on a Si substrate. The membrane is heated to a constant 80C above ambient temperature that is monitored by the substrate resistor. The membrane resistor is approximately 60 Ω and a constant substrate to membrane resistance ratio is maintained at 3.86. Figure 5.3b shows the Pirani die in cross section.
Since the first two losses are essentially constant at high vacuum for a given sensor, we can measure these losses and subtract them from the input power which leaves only the rate of heat transmission through the gas (Eg). In the viscous flow regime, the Eg loss is directly dependent on the thermal conductivity of the gas (Kg), the surface area of the membrane, the differential temperature and is inversely proportional to distance between the membrane and the lid.
Ta = ambient temperature P = pressure Ag = surface area of the heated portion of the membrane For nitrogen at a pressure of 760 Torr and a temperature of 20°C the mean free path (l) is less than 1 x 10-7 meters and is inversely proportional to pressure. Since the thermal transfer distance (Dx) is a few micrometers, this sensor will remain in the molecular flow regime at a much higher pressure (10 Torr) than is typical for a thermal vacuum gauge.
6. Communications Option Board Both RS-232 and RS-485 communication interface boards are available as an option for the Model 2002. The communication option boards allow data to be output to a host computer with the appropriate interface. Connection to the RS-232 or RS-485 communication interface boards are via a 9 pin D-subminiature female connector. 6.1. RS-232-E Interface Specifications Format....................................................
6.1.1. Interface Connector Pin Assignments for RS-485 (Full duplex-4 wire)(Jumper position 2-3). PIN MNEMONIC SIGNAL DESCRIPTION 2 TX+ 8 TX- Transmit + Differential data signal levels to Transmit - the RS-485 bus 3 4 RX+ RX- Receive + Differential data signal levels to Receive - the RS-485 bus 6.1.2. For RS-485 (Half Duplex – 2 wire) (Jumper position 1-2).
When a lower case character is present in an example it represents an option. Character Description Valid Inputs: a RS-485 Address (hexadecimal 0-9, A-F)........................................................01 - FF m Most Significant Digit Of Mantissa..................................................................... 1 - 9 d Decimal Digit ...................................................................................................... 0 - 9 e Exponent .....................................
Notes: The setpoints may also be entered as a decimal number, e.g. [H=760.99] will be same as entering [H=7.6099E+2] . When inputting setpoint data, it should be entered in the same Units of Pressure as the presently selected Units of Measurement (i.e. Torr, mbar or Pascal). The data is only checked to be a valid number with a one digit exponent before being accepted. There are no limit checks on the data; the user is free to choose any value appropriate to his use of the instrument.
Reset / Restore Commands Command Description Format Notes: Escape .......................................................................Reset Command Buffer .......................................................................................(Ignore prior Input) Software Reset /R ........................................................................ Reinitialize Software Restore Factory Defaults /# ...................................
7. Relay Interface Option Board The relay interface board is available as an option for the Model 2002. Additionally, relays may be added to either the Digital option Board (RS-232 or RS-485) or to the Analog option Board (0-10 Volts or 4-20mA). In either case the relays operate independently of the other options. The relay board allows the TTL logic setpoints (High, Low) to directly control two SPDT relays.
8. 4-20 mA Interface Option Board The Relay option board in the Model 2002 operates off of the set points defined by the user and programmed into the Model 2002 microprocessor. For more information about configuring these set points refer to Section 3 of this manual. The 4-20 mA interface board is available as an option for the Model 2002. This board provides dual current channels linearly proportional to the HPM 2002’s pressure reading.
8.2. Operation The 4-20 mA output option board provides dual channel current output linearly proportional to the HPM 2002’s pressure reading. The first channel corresponds to the higher pressure range (0-1024 Torr). The second channel corresponds to the lower pressure range (0-1000mTorr).
9. 0-10V Interface Option Board The 0-10 V interface board is available as an option for the Model 2002. This board provides dual voltage channels linearly proportional to the HPM 2002’s pressure reading. Please note that use of the Model 2002 with this option requires a CPU with firmware version 1.6 or later for proper operation. 9.1 0-10V Interface Connector Pin Assignmets Pin Connection 1..................................................................................................................
The 0-10V output option board, provides voltage outputs proportional to the HPM-2002 pressure reading. The first channel corresponds to the higher-pressure range (0-1024) Torr). The second channel corrresponds to the lower pressure range (0-1000mTorr). The equation below gives the output voltage for a given pressure. V (channel1) = P(Torr ) 100 V (channel 2) = P(mTorr ) 100 Where: V (channel 1) is the voltage between pins 1 and 3, V (channel 2) is the voltage between pins 8 and 7.
10. Troubleshooting Guide Symptom: Power on - No display activity. Action: 1. Check for proper AC voltage at the outlet. 2. Ensure that the AC power cord connectors are firmly seated in their sockets. (at the outlet and at the instrument.) 3. Check the fuse. a) Remove the power cord from the IEC-320 socket on the back of the instrument. b) Pry the fuse holder out of the socket assembly by using a screwdriver in the small slot inside the IEC-320 socket. c) Check the fuse that is in the fuse clamp.
11. WARRANTY 11.1. Warranty Repair Policy Hastings Instruments warrants this product for a period of one year from the date of shipment to be free from defects in material and workmanship. This warranty does not apply to defects or failures resulting from unauthorized modification, misuse or mishandling of the product. This warranty does not apply to batteries or other expendable parts, or to damage caused by leaking batteries or any similar occurrence.
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