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Group3 DTM-151 User Manual

Digital teslameter with ieee-488 gpib interface
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DTM-151
DIGITAL TESLAMETER
with IEEE-488 GPIB Interface
USER'S MANUAL
For units supplied with software DTMS V6.0
V7.0
&
20 July 2007
Group3 Technology Ltd., 2 Charann Place, Avondale, Auckland 1026. P.O. Box 71-111, Rosebank, Auckland 1348, New Zealand.
Phone: +64 9 828 3358
Fax: +64 9 828 3357
email: info@group3technology.com
web: www.group3technology.com

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  • Page 1 For units supplied with software DTMS V6.0 V7.0 & 20 July 2007 Group3 Technology Ltd., 2 Charann Place, Avondale, Auckland 1026. P.O. Box 71-111, Rosebank, Auckland 1348, New Zealand. Phone: +64 9 828 3358 Fax: +64 9 828 3357 email: info@group3technology.com...
  • Page 2 Fax: +64 9 828 3357 Email: info@group3technology.com Web: http://www.group3technology.com Group3 Technology Ltd., 2 Charann Place, Avondale, Auckland 1026. P.O. Box 71-111, Rosebank, Auckland 1348, New Zealand. Phone: +64 9 828 3358 Fax: +64 9 828 3357 email: info@group3technology.com web: www.group3technology.com...

  • Page 3: Table Of Contents

    CONTENTS 1. General Description 2. Specifications of DTM-151 System 3. Setting Up Introduction Connecting the Hall Probe Connecting the Power Source GPIB Connection Internal DIP Switch Settings Analog Outputs 3-10 Grounding 3-11 Installing the Panel Mount Option 3-12 Installation Techniques for Electrically Noisy Environments 3-13 4.
  • Page 4 DIP Switch Functions Table 3 String Terminator Switch Settings Table 4 Analog Output Connector Pin Assignments 3-10 Table 5 IEEE-488 Command Codes 4-10 Table 6 DTM-151-_G IEEE-488 Command Codes 4-14 Table 7 DTM-151-_G IEEE-488 Commands 4-15,16,17 Contents- DTM-151 (GPIB) User's Manual...

  • Page 5: General Description

    IEEE-488 GPIB interfacing for system applications. The instruments are light and compact, and the probes are easy to use. The DTM-151 has been engineered to withstand the severe electrical interference produced by high voltage discharge.
  • Page 6 IEEE-488 General Purpose Interface Bus. With the serial option, a single teslameter may be connected to standard RS-232C equipment, or up to 31 units may be interconnected on a Group3 Communication Loop (G3CL) and driven from computer or terminal. Fiber optic ports duplicate functions of RS-232C signals, for electrical noise immunity and voltage isolation.

  • Page 7: Specifications Of Dtm-151 System

    0.00005 0.01 0.000001 20-bit digitizing of field reading. Accuracy DTM-151 with LPT-141 or MPT-141 probe: ±0.01% of reading ±0.006% of full-scale max. at 25° C Temperature DTM-151 with LPT-141 or MPT-141 probe: Stability calibration: ±10 ppm of reading/° C max .
  • Page 8 Output responses field value in tesla or gauss followed by optional T or G and string terminator(s), system status, numerical data requested by commands, messages. DTM-151 (GPIB) User’s Manual...
  • Page 9 16 rates, switch selected, 50, 110, 134.5, 150, 200, 300, 600, 900, 1050, 1200, 1800, 2000, 2400, 4800, 9600, 19200 baud. System orientation Group3 Communication Loop (G3CL) using serial ports, simple loop for 31 devices, no multiplexer required; GPIB with IEEE-488 option.
  • Page 10 MPT series, miniature transverse types, sensitive area 1.0 x 0.5mm, probe head size: MPT-132 MPT-230 MPT-141 MPT-231: 14 x 5 x 2 mm Standard cable length: 2 meters. Special cable lengths to 30 meters. Probe cable is shielded. DTM-151 (GPIB) User’s Manual...
  • Page 11 0.3, 0.6, 1.2, 3.0 tesla full scale, support all LPT and MPT series probes, plugpack supplied except for option -L. DTM-151 (supports LPT-141, LPT-231, MPT-141, MPT-231 probes) Options Bench style instrument with display: add suffix -D |...
  • Page 12 DTM-151 (GPIB) User’s Manual...

  • Page 13: Setting Up

    A severed cable cannot be re-joined without altering the probe's performance, and requires factory repair and re-calibration. Your DTM must be used with a Group3 Hall probe. The probe may be one supplied with your teslameter, or it may have been obtained separately. In any case, calibration is preserved when probes are exchanged between instruments.

  • Page 14: Connecting The Power Source

    The standard probe cable length is 2 meters. Probes with non-standard cable lengths up to 30 meters may be ordered from your Group3 supplier. The cable used for Group3 probes is shielded to reduce pickup of induced noise from external sources. Such noise may reduce the accuracy of the instrument, cause malfunctioning, or in extreme circumstances even result in damage to the internal circuitry.

  • Page 15: Fig. 1 Power Input Connections Of The -L Option

    Suggested fuse ratings are 200 mA for 115 volts, or 100 mA for 208 and 230 volt operation. When the unit is first powered up, the display shows Group3 for 2 seconds before field measurements appear. If the Hall probe is not plugged in, the field reading display is replaced with noProbE.

  • Page 16: Gpib Connection

    GND 9 Ground wire of twisted pair with IFC GND 10 Ground wire of twisted pair with SRQ GND 11 Ground wire of twisted pair with ATN Teslameter logic ground Table 1. GPIB Connector Pin Assignments DTM-151 (GPIB) User’s Manual...

  • Page 17: Fig. 2 Ieee-488 Standard Connector

    SHIELD SRQ NDAC DI04 DI02 NRFD DI03 DI01 11 10 23 22 21 20 18 17 16 DI07 DI05 LOGIC DI08 DI06 Fig. 2. IEEE-488 Standard Connector DTM-151 (GPIB) User’s Manual...

  • Page 18: Internal Dip Switch Settings

    Refer to Fig. 3 for switch locations. Switch functions are as follows: 8-way DIP switch - sets device address on GPIB; sets talker-only mode. 8-way DIP switch - selects operation mode and communication options. DTM-151 (GPIB) User’s Manual...

  • Page 19: Fig. 3 Location Of Processor Board Switches

    * no action defaults loaded * factory setting Table 2. DIP Switch Functions The switches are read by the processor once per second, so the effects of changed settings can be observed in real time. DTM-151 (GPIB) User’s Manual...

  • Page 20: Table 3 String Terminator Switch Settings

    S2-3,4 is as follows: S2-3 S2-4 cr, lf lf, cr Table 3. String Terminator Switch Settings Check which terminator characters are required by the system controller and/or other devices in your GPIB system, and set the switches accordingly. DTM-151 (GPIB) User’s Manual...
  • Page 21 OFF again. If the switch is left ON, defaults will be loaded each time the teslameter is powered up. The display shows the message rESEt each time defaults are loaded. When defaults are loaded on power up, the rESEt message follows the Group3 power up message.

  • Page 22: Analog Outputs

    0.2 seconds. The rectifier circuit responds to the average value of the ac waveform, but is calibrated such that if the waveform is sinusoidal, the reading corresponds to its rms value. The output impedance is the same as for the dc output. 3-10 DTM-151 (GPIB) User’s Manual...

  • Page 23: Grounding

    Group3 ferrite kit part no. 11000036. See section 3.9 of this manual. For electrical safety, the case of the L version must be grounded through the third wire of the power input cord.

  • Page 24: Installing The Panel Mount Option

    3.8 INSTALLING THE PANEL MOUNT OPTION Model DTM-151-PG is supplied fitted with a special front bezel which has threaded studs to allow panel mounting. A panel mount support bracket (part 17000058) is included to help support the teslameter. Group3 can supply 19-inch wide, 2U (3.5") high rack panels to hold one, two, or three teslameters (parts 17000025, 17000026, and 17000027, respectively).

  • Page 25: Installation Techniques For Electrically Noisy Environments

    3.9 INSTALLATION TECHNIQUES FOR ELECTRICALLY NOISY ENVIRONMENTS The DTM-151 is a precision electronic measuring device. Because of the nature of the measurements it is asked to do, it is frequently exposed to conditions that are considerably worse than are normally encountered by precision instruments. Therefore,...
  • Page 26 Use a heavy gauge, short wire to ground the unit to a substantial grounding point nearby. If the teslameter is sitting on metalwork, then it should really be grounded to that metalwork so it is at the same potential. 3-14 DTM-151 (GPIB) User’s Manual...
  • Page 27 300mm back from the probe head. Group3 can supply an alternative power supply to be used instead of the usual plugpack. The alternative power supply is model PS12D7. It is a universal voltage (85 - 270V 50/60Hz) input, 12Vdc 7W output unit with excellent input-output isolation for noise and transients.
  • Page 28 3-16 DTM-151 (GPIB) User’s Manual...

  • Page 29: Operating Instructions

    4 OPERATING INSTRUCTIONS 4.1 ZEROING The DTM-151 digital teslameter has a very stable zero field reading. Nevertheless, it is good practice to zero the instrument on all ranges immediately prior to making critical field measurements. The zeroing process takes out residual zero errors in the Hall probe and the instrument's preamplifier "front-end".

  • Page 30: Installing The Probe

    4.2 INSTALLING THE PROBE Group3 Hall probes are built to be as robust as possible for a small, precision device. However, it is most important that certain precautions be taken when handling and installing probes so that they are not damaged or destroyed, and to preserve their accurate calibration.

  • Page 31: Reading The Field Value

    Change to a higher range until the message clears. The field may be displayed in tesla or gauss, with the appropriate indicator showing the units in use. To change the units, see section 3.5. DTM-151 (GPIB) User’s Manual...

  • Page 32: Display Modes, Using The Front Panel Keys

    Reset is performed by pressing both keys together. The peak value is also reset if the field polarity changes. d. Peak ac measurement. Combination of b. and c. above. e. Probe temperature display in degrees Celsius. DTM-151 (GPIB) User’s Manual...
  • Page 33 4.4.3 Display Messages Power up message The message Group3 appears in the display for 2 seconds when the teslameter is first powered, or when a GPIB command restarts the operating software (see section 4.5.3). No Probe The message noProbE is displayed if the Hall probe is disconnected from the instrument.
  • Page 34 With the teslameter in dc field display mode, when the MODE key is pressed twice very quickly the display shows Addr nn where nn is the address of the teslameter as set on switches S1-1 though S1-5. Press the mode key once again to cancel this display. DTM-151 (GPIB) User’s Manual...

  • Page 35: Using The Ieee-488 Gpib Interface

    DEVICE B ONLY ABLE TO LISTEN Data DEVICE C DATA BYTE TRANSFER CONTROL ABLE TO TALK AND LISTEN GENERAL INTERFACE MANAGEMENT DEVICE D ONLY ABLE TO TALK DIO 1...8 NRFD NDAC Fig. 6. A Typical IEEE-488 System DTM-151 (GPIB) User’s Manual...
  • Page 36 The controller then releases the ATN line, thus allowing the talker to start sending its data on the bus. The ATN line distinguishes commands from data. When a controller is about to set up such a DTM-151 (GPIB) User’s Manual...
  • Page 37 ATN line is held asserted. This causes the device whose address is decimal 18 to become a listener. In IEEE-488 parlance, the device is said to be "selected". Any or all devices on the bus, which have listener capability, may be in the selected state simultaneously. DTM-151 (GPIB) User’s Manual...

  • Page 38: Table 5 Ieee-488 Command Codes

    To cause all listeners to stop listening, the controller sends the Unlisten command, decimal 63 (hex 3F, ASCII ?). To stop the talker being a talker, the Untalk command is sent, i.e. decimal 95 (hex 5F, ASCII_). 4-10 DTM-151 (GPIB) User’s Manual...
  • Page 39 2) ascertain the action required (serial poll) 3) execute the required action 4) re-enable interrupts 5) return to the task in hand before being interrupted. The SRQ line is released by the device when the serial poll is performed. 4-11 DTM-151 (GPIB) User’s Manual...
  • Page 40 The devices are not addressed to listen before this command. • The PPC command followed by Parallel Poll Disable (PPD) will disable parallel polling only in devices which have been selected (addressed to listen). 4-12 DTM-151 (GPIB) User’s Manual...
  • Page 41 4.5.2 DTM-151-_G IEEE-488 Capability The IEEE-488 Standard defines ten interface functions, some with as many as 28 allowable subsets. The DTM-151-_G teslameters support the interface functions as listed below. See also Appendix C of the IEEE-488-1978 Standard. source handshake capability...

  • Page 42: Table 6 Dtm-151-_G Ieee-488 Command Codes

    3.5. This mode is used in systems which have no system controller, in which the teslameter continuously sends field readings on the bus to listener-only devices, for example printers, terminals, or the Group3 COM-488 IEEE-488 to Serial Adaptor, which converts the bus traffic to serial data format.

  • Page 43: Table 7 Dtm-151-_G Ieee-488 Commands

    All responses from the teslameter start with a space character. Decimal numbers include a decimal point. Some are in exponential format. If an error message is returned, the complete command must be re-entered. TABLE 7. DTM-151-_G IEEE-488 COMMANDS command description B<text><cr>...
  • Page 44 Range selection, selects 0.3 tesla range. Range selection, selects 0.6 tesla range. Range selection, selects 1.2 tesla range. Range selection, selects 3.0 tesla range. Set calibrate - enters calibration factor n for the selected range; 4-16 DTM-151 (GPIB) User’s Manual...
  • Page 45 Restarts operating software as if teslameter had been freshly powered up. CTRL X Reload defaults - all default values reinstated. Message RESET is sent. Note: SFn, STn, SWAn, SWEn, SWZn modes are cancelled by GPIB commands SDC and DCL – see Table 6, section 4.5.2. 4-17 DTM-151 (GPIB) User’s Manual...
  • Page 46 SPAS (serial poll active state) and completes the handshake for the serial poll status byte. 4-18 DTM-151 (GPIB) User’s Manual...
  • Page 47 The status bit in the serial poll response will always be asserted if there is data available to be read. The SRQ bit is reset to the false state after the serial poll, and is only re- enabled when data is read from the teslameter. 4-19 DTM-151 (GPIB) User’s Manual...

  • Page 48: Digital Filtering

    41 for J is effective when the DTM is reset with the CTRL X command or S2-8. This gives an effective time constant of 4 seconds. The filter time constant may be changed by entering a new value of J using the Jn command. See section 4.5.3. 4-20 DTM-151 (GPIB) User’s Manual...

  • Page 49: Triggered Operation

    LED will be seen to flash about twice per second. After the GV command the LED will stop flashing. Then each time the GET or V command is given, the LED will flash once. Continuous operation is restored using the GC command. The following sections describe details of triggered operation. 4-21 DTM-151 (GPIB) User’s Manual...
  • Page 50 The unit will zero correctly in triggered mode if first the V command is given while the probe is in zero field with filtering off; then the Z command (or pressing both keys together) will zero the instrument. 4-22 DTM-151 (GPIB) User’s Manual...

  • Page 51: Display Board Schematic

    The schematics, component overlays, and parts lists of the four circuit boards in the DTM-151 GPIB interfacing teslameter and probe are provided for general reference. It is not recommended that the user attempt repair or servicing because in many cases replacing parts will affect the calibration of the instrument.
  • Page 52 DTM-151 (GPIB) User’s Manual...

  • Page 53: Limited Warranty

    GROUP3 TECHNOLOGY LTD LIMITED WARRANTY Group3 Technology Ltd. (hereinafter called the Company) warrants instruments and other products of its manufacture to be free from defects in materials and workmanship that adversely affect the product's normal functioning under normal use and service for a period of one year from the date of shipment to the purchaser.
  • Page 54 Group3 Technology Ltd - DISTRIBUTORS & REPRESENTATIVES European Region United Kingdom Pulse Power & Measurement Ltd 65 Shrivenham Hundred Business Park Watchfield, Swindon, Wiltshire, SN6 8TY, UK Tel: +44 (0)1793 784389 Fax: +44 (0)1793 784391 email: sales@ppm.co.uk website: www.ppmpower.co.uk Denmark, Sweden, Norway, Finland, Iceland, Belgium, Holland, Italy, Turkey, Russia, India Danfysik A/S Møllehaven 31, P.O.

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