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TH1941 Multimeter

1. DC AC E O 727g TH1942 50000 Count Multimeter ACV MED AUTO n Per iod Dun kHz m LI INL dB dBm Vor 20 LOBaV RE SA Rel Wax Min c SH 2nd Hold GAN A Rate Trig W O AH zi Pi 4 gt v J A Ae cs a TIAL 29 ALL INPUT J g pas L J ift 1KV MAX Nee POWER AC VOLTAGE SOURCE 5 j l 7 Frequency Measurement Stat ET ES DC AC el z0nglul TH1942 50000 Count Multimeter DC V A6 V MED AUTO i Period 1 ILI E 2 Frea 0999Hm5 J i O GtdamVAL E Rel Wax Min 2nd Hold Rate Trig Menu Local 20 GI CI GIGI 9 J e mm l ar v POWER AC VOLTAGE SOURCE A Period Measurement Input Impedance 1 1MQ in parallel with 100pF CAUTION Maximum Input 750V RMS or 1000V peak 3 X10 V Hz Figure 3 4 Frequency and Period Measurements 3 6 Measuring Continuity Under continuity test when 2000 range is selected the multimeter alerts you with a beep when a reading is below a threshold resistance level of 10Q For other ranges the beeper will sound if a reading is below a threshold resistance level listed in table 3 1 Table 3 1 Threshold resistance levels in Continui
2. 2 Press for diode measurement function 3 Connect test leads to the diode under test as shown in Figure 3 6 4 Take a reading from the display d DC I AC O Tongiut TH1942 50000 Count multimeter DC V AC V d MED E Per iod CE Freq 0900 VIL s AC DC gt Comp Rel Max Min 2nd Hold Rate Trig Menu Local a GICI GIGI 9 Go m mh xum PONER Me o o DIODE ZT Note Source current flows from the VQ to COM terminals Figure 3 6 Diode Measurement 3 8 Measuring True RMS AC DC Model TH1942 can measure the True RMS value of AC DC voltages and currents When is pressed the multimeter will measure the dc and ac signals respectively then calculate and display the AC DC RMS value by using the following formula AC DC RMS V dc ac 3 8 1 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is as follows Connect test leads to VO and COM terminals as shown in Figure 3 7 Press Pev cv sun pcv or sit cv to select a voltage or current measurement Press for true RMS measurement function Press hit Rate to turn on a 2 display Press or LP to select a 2 parameter available Take a reading from the display D l e o Noa N
3. S JT8Bghui TH1942 50000 Count multimeter MED AUTO irm JAT Hb dcm AI Bib 5l dim CeO DS em mm ae L 31 POWER VOLTAGE SOURCE Z S DC AC RMS volt measurement TH1942 50000 count Multimeter N AUTO e Ut ge mHRI LODODO KHZ ON OFF POWER ALL INPUT 1KV MAX V V CURRENT SOURCE A DC AC RMS current measurement Figure 3 7 True RMS value of AC DC voltages and currents Measurement Wome amp a 2 3 8 2 Using the 2 parameter display The 2 display is one of the useful features provided with the multimeter User may read two different parameters at the same time The available 2 display parameters under different main measurement functions are listed in Table 3 2 Table 3 2 Available 2 display parameters for different measurement functions Secondary Display Primary Display gt ED DC V AC V dBm dB Hz AC V DC V dBm dB Hz DC V AC V dBm dB Hz AC V DC V DC AC Hz AC DC Hz DC I AC I Hz AC DC Hz AC V AC AC I AC V Percentage Measuring value Comp Measuring value Max Min Measuring value H
4. Primary TH1942 50000 Count Multimeter Displa FAST MED SLOW TRIG HOLD AUTO REL MATH 3 E ac NUN aM A Seconda y Frrr FF Max Min Hold oN pi lenu Local bl lt a gt v a t Shift CIR E83 2 C3 C3 093 e Switch J 5 Range 4 Menu 3 2 Display 7 Shiftlocal 6 Hold Trig Selection Operation And speed keys Keys Keys COMP RT BN EO RMT AUTO MAX MIN BHH SHIFT Display Current Input fuse Figure 2 1 TH1942 Front Panel 1 Measurement Function keys shifted and unshifted Select measurement function DC voltage and current AC voltage and current resistance continuity frequency period dB dBm True RMS AC DC and diode test 2 Math function keys Select the math function Rel Max Min Comp and Hold 3 2 Display and speed key Changes reading rate Fast Medium and Slow F turn on or off the 2 parameter display 4 Menu operation keys Shift Open Close menu 4 Move through selections within menu level command level or parameter level gt Move through selections within menu level command level or parameter level A Move up a level v Move down a level ENTER Save the change made on parameter level and return to the command level Cancel the change made on parameter level and return to the command level 5 Range and Combin
5. VLL La DC Current measurement at Range 5mA 50mA 500mA s a DC AC 6 72895 TH1942 50000 Count Multimeter Dc v ac v ANSE aon m D Period ETT RES O1005mANC RR Rel pS ZA e IANN N Rate Crie ON OFF f Menu Local T Aut C sniet ALL INPUT B O89 C3 GIGI G9 emo mo me ge L IMEEM E AC CURRENT SOURCE POWER QE i AC Current measurement at Range 5mA 50mA 500mA J TH1942 50000 Count Multimeter AUTO 3ODUURRIC i acoc gt ig amp 3 aRRLE EC em 2nd Hold E Rate Trig Ai M Local qT Owna as L POWER i Aino VQ O 1000V M 4 A m M 20A Nc TIAL 250V ALL INPUT 1KV MAX DC Current measurement at Range 5A 20A en A J LT Vv m DC CURRENT SOURCE s el Fang TH1942 50000 Count Multimeter ac V m MED AUTO n Per iod j Freq cl Lg mHRRE db dBm Ua LrSaRIE X uw Max Min 2nd Hold J Rate Trig Menu Local 2C oaoa e ae POWER CAT croo0y AT II 300V
6. Speed Commands NPLCycles lt n gt Command Systac CURRent AC NPL Cycles lt n gt CURRent DC NPLCycles n Set NPLC for ACI Set NPLC for DCI Command Parameter lt n gt 0 1to 10 Set power line cycles per integration DEFault 1 MINimum 0 5 MAXimum 2 Query NPLCycles Query programmed NPLC value Description The integration period measurement speed for the basic measurement functions except Frequency and Period is set using the NPLCycles command NPLC Number of Power Line Cycles expresses the integration period by basing it on the power line frequency For example for a PLC of 1 the integration period in seconds would be1 60 for 60Hz line power which is 16 67 msec RANGe Commands UPPer lt n gt Command syntax CURRent AC RANGe UPPer n Set measurement range for ACI CURRent DC RANGe UPPer n Set measurement range for DCI Command Parameter lt n gt 0to20 Expected reading is AC volts ACI 20 to 20 Expected reading is DC volts DCI DEFault 20 ACI DCI MINimum 0 All functions MAXimum Same as DEFault Query RANGe UPPer Query measurement range of the current functon Description This command is used to manually select the measurement range for the specified measurement function The range is selected by specifying the expected reading as an absolute value The instrument will then go to the most sensitive range that will accommodate that expected reading F
7. exit 1 send port PORT n send command end symbol delay 2 while check stat PORT amp 256 read port PORT read string from serial port void string rd char ps unsigned char cji for i 0 lt 255 i max read 256 characters while check stat PORT amp 256 wait serial receive ready if kbhit amp amp getch 27 if escape key keypress printf nE21 Serial Port Read Canceled exit 1 c read_port PORT if c n break pS c pS send a character to serial port void send port int port char c union REGS r r X dx port serial port r h ah 1 int14 function1 send character rh al c character to be sent int86 0x14 amp r amp r if h ah amp 128 check ah 7 if set by int86 0x14 amp r amp r mean trans error printf nEO0 Serial port send error exit 1 read a character from serial port char read port int port union REGS r r X dx port serial port r h ah 2 int14 function2 read character int86 Ox14 amp r amp r if h ah amp 128 if ah 7 be set mean trans error printf nEO1 Serial port read error exit 1 return r h al check the status of serial port int check stat int port union REGS r r X dx port serial port r h ah 3 int14 function3 read status int86 0x14 amp r am
8. Slow Slow sets speed to 5 readings per second SLOW provides better noise performance at the expense of speed Note The integration time can be set for any measurement function except frequency period continuity FAST and diode test Medium For frequency and period this value is little excess a gate time 4 2 Trigger Operations The multimeter s triggering system allows you to generate triggers either manually or automatically or externally and take multiple readings per trigger The following paragraphs discuss front panel triggering and the reading hold feature 4 2 1 Trigger flow Wait for Trigger The control source holds up operation until the programmable event occurs and is detected See description below for trigger sources B Immediate With this trigger source event detection is immediately satisfied allowing operation to continue B External Event detection is satisfied for both kinds of triggers as below 1 Abus trigger TRG command is received 2 The front panel Tie key is pressed TH1942 must be taken out of remote before it will respond to Te key Take steps below for trigger settings 1 Press 9 to enter the menu on the menu level A MATH MEU will be displayed 2 Usel 4 o gt key to move across to the TRIG MEU on the menu level B TRIG MEU will be displayed 3 Press W to move down to the command level within the TRIG MEU 4 Usel d o key to move across to the TRIG MODE command on the c
9. Press sit Es to enter the menu on the menu level A MATH MEU will be displayed Press W to move down to the command level within the MATH MEU 3 PERC REF will be displayed Press W to enter the parameter level and the present reference value will be displayed 41 000004 Use 4 an gt keys to choose a numerical place and use A ady keys to increment or decrement the digits Enter a value and units prefix Press ENTER to confirm the reference value SAVED will be displayed for a moment and TH1942 will return to the command level Press to cancel the reference value input TH1942 returns back to the command level without changing the reference value Press shin key to exit the menu and return to the percent math operation status Model TH1942 will display measurement result of calculation If the value of Input is larger than that of Reference displayed result will be positive contrarily it will be negative if the value of Input is smaller than that of Reference 3 9 2 dB Calculation Expressing DC and AC voltage in dB makes it possible to compress a large range of measurements into a much smaller scope The relationship between dB and voltage is defined by the following equation dB 20log Vu REF Where V is the DC or AC input signal Veer is the specified voltage reference level The instrument will read OdB when the reference voltage level is applied to the input If
10. shire Esc Menu To turn off the menu press shite Ese Menu or press any of the function or math keys on the front panel To confirm a change on the parameter level press ENTER Tocancel a change on the parameter level press Esc Menu Note Ifyoupress A onthe menu level this is the top level of the menu and you can not go any higher similarly if you press on the parameter level this is the bottom level of the menu and you can not go any lower 2 5 Rear Panel Summary The rear panel of TH1942 is shown in Figure 2 4 This section includes important information that should be reviewed before operating the instrument 1 2 3 NN l Rs 2320 Ca d 4 onj al 10VA Max A WARNING ue THE PONER CORD PROTECTIVE GROUNDING RATING FUSE E NAPR CONDUCTOR MUST BE CONNECTED TO GROUND 110V 60Hz TIAL I j pm READS FUSE 220V 50Hz T500mAL ED M VN ot e a J i Wo J U 4 Figure 2 4 TH1942 Rear Panel 1 RS 232C Connector Connector for RS 232 operation Use a standard DB 9 cable 2 Grounding Chassis Grounding terminal 3 Power Line Fuse Holder Assembly TH1942 can be configured for line voltage of 110 220V 10 AC at line frequency of 50 60Hz 5 Power line fuse is used for instrument protect
11. AC CURRent DC FREQuency PERiod DIODe CONTinuity FUNCtion Query function FUNCtion Command FUNCtion lt name gt Command syntax FUNCtion lt name gt Command Parameter lt name gt VOLTage AC Select AC Voltage VOLTage DC Select DC Voltage CURRent AC Select AC Current CURRent DC Select DC Current RESistance Select 2 wire Resistance FRESistance Select 4 wire Resistance FREQuency Select Frequency PERiod Select Period DIODe Select Diode Testing CONTinuity Select Continuity Testing Query FUNCtion Query currently programmed function Description This command is used to select the measurement function of the instrument Note that the parameter names are enclosed in single quotes However double quotes can instead be used For example FUNC VOLT FUNC VOLT Each measurement function remembers its own unique setup configuration such as range speed filter and rel This eliminates the need to re program setup conditions every time you switch from one function to another 6 3 3 VOLTage subsystem The commands in this subsystem are used to configure and control voltage measurement function and are summarized in Table 6 3 Table 6 3 VOLTage Subsystem Commands Summary Command Function Description Default VOLTage DC Path to configure DC voltage NPL Cycles lt n gt S
12. Panel RS232 Interface Connection between TH1942 and a computer shown as Figure 5 2 DTR 4 DSR 6 RXD 2 Computer TXD 3 3 TXD THI951 GND 5 RTS 7 CTS 8 Figure 5 2 RS 232 Connection Sketch There may be some difference between TH1942 RS232 interface and a standard RS232C interface You can make the connection cable by yourself according the diagram or order one from our company Note Pin 4 and 6 pin 7 and 8 are shorted respectively at the end of controller 5 2 2 Sending and receiving data Model TH1942 transfers data using 8 data bits 1 stop bit and no parity Each program message that is transmitted to the controller is terminated with LF Line Feed ASCII code is 10 5 2 3 Selecting Baud Rate The baud rate is the rate at which Model TH1942 multimeter and the computer communicate Choose one of these available rates m 38 4k 19 2k 9600 4800 2400 1200 600 Note Factory default baud rate is 9600 Before you choose a baud rate make sure the programming terminal that you are connecting to the TH1942 can support the baud rate you selected Both the multimeter and the other device must be configured for the same baud rate Perform the following steps to select a baud rate 1 2 8 Press Shit to enter the menu on the menu level A MATH MEU will be displayed Use 4 or B key to move across to the SYS MEU on the menu level C SYS MEU will be displayed
13. Press W to move down to the command level within the SYS MEU 1 BEEP STR will be displayed Use 4 or B key to move across to the BAUD RATE command 2 BAUD RATE will be displayed Press V to move down a level to set the baud rate Use 4 or gt key to select a baud rate Press ENTER to confirm the selection The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command level Press Sit key to exit from the menu and return to the measurement status 5 2 4 Software Protocol Since the hardware handshaking lines CTS and RTS are not used by TH1942 the multimeter uses the character return method to decrease the data losses and errors during communication Please refer to the content below before programming communication software 1 2 For command syntax and format refer to Chapter 6 Command Reference The controller transmits the command using the ASCII code with lt LF gt or lt CR gt as the terminal character TH1942 executes the command after the terminal character is received The character received by TH1942 will be sent back to the controller again The controller will not send the next character until the last returned character is received correctly from TH1942 If the controller fails to receive the character sent back from TH1942 the possible reasons are listed as follows The serial interface is not con
14. TA auos NT 7 Tel Feature Overview sid t ERREUR RA RM ERREUR RM REM MSIE 7 1 2 Operating Environment 5 3 hetero He e RU e EE TE E E ET D ERE LER EE t e TESES sacs 7 1 3 Drimensions and Weight cro tre rm ert HE E He Pere FER E Fe ERE eO Fr FERRI OI esr Mee 7 1 4 Safety symbols and Precautions eee Ce e ON CR ER NE ON CR Rd 8 LS Incoming Inspection eee ertet rte tenter Er enn Yn Eee AEA Erbe rn ARUU ek arbe rien etes ao erae ndo 8 1 6 uacua 9 1 7 Limitation of Warranty etti er reet ie epe M HORE EE rc aedi te reete edet 9 Chapter 2 TH1942 COV RIV OW M TE 10 2 1 Front Panel Summary T niana aE AEEA EAAS 10 2 2 Annunciators On SCreen viccisccisecvsccveecvaccvaccvaccvaecvaccvaaevaccvaecvaccvaecuascvasevaccvadevaacvasevascvaeseasevaseuasevadeeaacvaaeeasevuaes 11 2 3 Front Panel Menu Reference sianainatinon a AEE ENEN NENE ENE ONENEN 12 2 4 Front Panel Menu OVervieW eere ERE RETE e RE AEA E E EC E e EE CR ERN YR EUER Cet 13 2 9 Reat Panel Summary M M 14 2 0 POWEL UP we 15 2 6 1 Power Line Connection canta iq ten na len uaa cmacaincabacaontactuesnacasinessumaumsaucaiucoianeaiuereciaccinie 15 2 6 2 Input Terminals rre t rper etras i de e p ea eh ira ett Fin En 15 2 6 3 Power up SOgUsriGea qudm stur tete sto ni net ot RA Unda nrbt Univ intUs Und RA UE 16 2 6 4 High Energy Circuit Safety Precaution
15. The last command sent REFerence n or ACQuire eatablishes the reference When a reference is set using the REFerence n command the REFerence Query command returns the programmed value Conversely when a reference is set using the ACQuiry command the REFerence Query command returns the acquired reference value STATe b Command syntax VOLTage AC REFerence STATe lt b gt Control reference for ACV VOLTage DC REFerence STATe lt b gt Control reference for DCV Command parameter lt b gt 10rON Enable reference 0 or OFF Disable reference Query STATe Query state of reference Description These commands are used to enable or disable Reference for the specified function When enabled the displayed reading will include the programmed reference value When disabled the displayed reading will not include the reference value ACQuire Command syntax VOLTage AC REFerence ACQuire Acquire reference for ACV VOLTage DC REFerence ACQuire Acquire reference for DCV Description When one of these commands is sent the measurement input signal is acquired and established as the reference value This command is typically used to zero the display For example if the instrument is displaying a 1uV offset sending this command and enabling Reference zeroes the display This command is functional only if the instrument is on the specified measurement function Sending this command while in any other function causes an er
16. V Q gt A TIAL 250V ALL INPUT 1KV MAX y V AC CURRENT SOURCE Ww J AC Current measurement at Range 5A 20A CAUTION Maximum Input 20A DC or RMS Maximum test times Figure 3 2 DC and AC Current Measurements 3 3 2 Front Panel Fuse Replacement I ML 20s WARNING Make sure the instrument is disconnected from the power line and other equipment before replacing the AMPS fuse 1 Turn off the power and disconnect the power line and test leads Take the fuse carrier out of the socket From the front panel use a screwdriver to rotate the fuse carrier several turns counter clockwise Remove the fuse and replace it with the same type T1AL 250V 5x20mm CAUTION Do not use a fuse with a higher current rating than specified or instrument damage may occur If the instrument repeatedly blows fuses try to find out the reason before replacing the fuse 4 Install the new fuse by reversing the procedure above 3 4 Measuring Resistance Model TH1942 Resistance measurement range 5000 5kO 50kO 500kO 5MQ 50MO Maximum resolution 10mQ on 5000 range 3 4 1 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is as follows 1 2 3 Connect the test leads to VQ tand COM Select resistance measurement function by pressing Press toggles auto ranging Notice the AUTO annunciator is disp
17. as follows 1 2 3 Connect test leads to 500mA terminal and COM terminal or 20A terminal and COM terminal Select DCI or ACI measurement function by pressing sum pcv or shit Aacv Press toggles auto ranging Notice the AUTO annunciator is displayed with auto ranging If you want manual ranging use the RANGE A and V keys to select a measurement range consistent with expected current Connect test leads to the source as shown in Figure 3 2 gt Te 1 lt CAUTION Do not apply more than 1A 250V to the 500mA input terminal or the fuse will be open circuit 5 f the OVL D message is displayed press up A key to select a higher range until a normal reading is displayed or press key for auto ranging Use the lowest possible range for the best resolution 6 press Shit Rate to turn on the 2 parameter display Use ioe gt key to move across 2 display parameters 7 Take readings from the display DC AC E FOR G HHT TH1942 50000 Count multimeter oe v AC V ANSA eoo gt H MED AUTO i Period VA d IAA TI Co Freq E UMT UL dB dBm Goe C gt F J T4 l X A D 1207 nRRE gt Oc Rel Wax Min A mh 2nd Hold RES LE P f N O Rate Trig M WY m ON OFF Menu Local NL LS AL GI C E03 GE O ap rmm sum 4 a POWER DC CURRENT SOURCE
18. be present on the terminal s Be careful to avoid personal contact with these voltages The symbol on the instruments means earth grounding The WARNING heading used in the manual explains high voltage danger that might result in personal injury or death Always read the associated information very carefully before performing the indicated procedure The CAUTION heading in the manual reminds user that hazards could damage the instruments if not according to operating instructions Such damage may invalidate the warranty 1 5 Incoming Inspection The TH1942 was carefully inspected mechanically and electrically before shipment After unpacking all items from the shipping carton please check for any obvious signs of physical damage that may have occurred during transportation Report any damage to the shipping agent immediately Save the original packing carton for possible future reshipment The following items are included with every Model TH1942 order Model TH1942 50000 Count Multimeter Test leads Model TH26036 Power cord Two 500mA fuses Two 1A fuses Operation Manual Quality and warranty certificate Test report Other optional accessories if ordered Verify that you have received all the items above when you get multimeter If anything is missing please contact our representative or our sales office 1 6 Warranty Tonghui warrants this product to be free from defects in material and workmanship for a period of 2 years f
19. blue above the key To perform a shifted function press sin the Shift annunciator will turn on Then press the key that has the desired label above it For example to select the AC current function press st then press ev ACI If you accidentally pressi S just press it again to turn off the Shift annunciator 3 2 Measuring Voltage Voltage ranges 500 mV 5 V 50 V 500 V 1000 V 750 VAC Maximum resolution 100 V on 500mV range AC technique true RMS ac coupled 1000V Peak AC 3 2 1 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is as follows 1 Connect test leads to VOX and COM terminals 2 Select DC or AC voltage measurement by pressing cv ofa 3 Press toggles auto ranging Notice that the AUTO annunciator is displayed with auto ranging If you want manual ranging use the RANGE A and V keys to select a measurement range consistent with expected voltage 4 Connect test leads to the sources as shown in Figure 3 1 CAUTION Do not apply more than 1000V peak to the input or instrument damages may occur 5 If the OVL D message is displayed press the up A key to select a higher range until a normal reading is displayed or press key for auto ranging Use the lowest possible range for the best resolution 6 press Shit Rate to turn on the secondary display Use oe gt key to move across to select the combination functions 7 Take readings from the displa
20. eee rave epe ree eee Pe ee ene Rees 46 Bo T DISPIay SUBS SIT occu m instead denda o nn QU iR tonc AE E hon Metu MU 46 9 3 2 FUNGON SUDSVSIBITI otii trs uci eoe evi urs onsite dun oi quas evi durs etus os bius 48 6 3 3 VOLTAGE SUBS YS LIN M 49 6 3 4 CURRent subsystem sic cus reanaccnstinovsnsaanneepaceestonsesanniuncpensdemsbanaceonnas eieaanpienracaplembacmamoensmaents 53 6 3 5 RESlister SUVS 19s tena n MUSEUMS UR Use MURDER UEM nIMq tM ERAN UK NER 57 6 3 6 FREQUENCY and PERIO subsystem cs sisssaccssvcsaticnsiscvatasienoaesrsdunativevtunteaiisnwsydeneaiueiivesnsndinatnivs 60 6 3 7 HOLD Sub Sy St SW ioiii sinian asiaan cannar aaia a e A a Ea aaiae 62 6 39 8 TRIGger SUBSYSTEM BP 64 6 3 9 FETCH SUD SY SIS Mi assntsdvvchedunsicheles chahatasabchatndaneisdshilebelanabibabssanenedthededetsadinbeenaboatsasmnsldebedbanoes 64 6 310 Common Command Ss sissisats cscs sta cian iaasstansacttnca leva cuansnavaawaiaeucnrdusngnusviansinsbaancaeibirntaciaainliiin 65 Chapter 7 SpPeCiHCatiONS seisseen M 66 Chapter 8 Program EXsmpl s ssaustisneu tin crag vxeinon P dra eso ae Pecunia ee a a EENES E 71 Chapter 1 General Information Thanks very much for choosing and using our product If you have any questions after reviewing this manual please contact your local representative or call directly to our application engineers for further consultation 1 1 Feature Overview TH1942 is a 50000 count dig
21. except Frequency and Period is set using the NPLCycles command NPLC Number of Power Line Cycles expresses the integration period by basing it on the power line frequency For example for a PLC of 1 the integration period in seconds would be1 60 for 60Hz line power which is 16 67 msec RANGe Commands UPPer lt n gt Command syntax VOLTage AC RANGe UPPer lt n gt Set measurement range for ACV VOLTage DC RANGe UPPer n Set measurement range for DCV Command Parameter lt n gt Oto 757 5 Expected reading is AC volts ACV 0 to 1010 Expected reading is DC volts DCV DEFault 757 5 ACV 1000 DCV MINimum 0 All functions MAXimum Same as DEFault Query RANGe UPPer Query measurement range of the current function Description This command is used to manually select the measurement range for the specified measurement function The range is selected by specifying the expected reading as an absolute value The instrument will then go to the most sensitive range that will accommodate that expected reading For example if you expect a reading of approximately 20mV simply let the parameter n 20 02 or 20e 3 in order to select the 200mV range AUTO lt b gt Command syntax VOLTage AC RANGe AUTO lt b gt Set auto range for ACV VOLTage DC RANGe AUTO lt b gt Set auto range for DCV Command parameter lt b gt 10rON Enable auto range 0 or OFF Disable auto range Query AUTO Query auto range
22. lt n gt 0 5102 Set power line cycles per integration DEFault 1 MINimum 0 1 MAXimum 10 Query NPLCycles Query programmed NPLC value Description The integration period measurement speed for the basic measurement functions except Frequency and Period is set using the NPLCycles command NPLC Number of Power Line Cycles expresses the integration period by basing it on the power line frequency For example for a PLC of 1 the integration period in seconds would be1 60 for 60Hz line power which is 16 67 msec RANGe Commands UPPer lt n gt Command syntax RESistance RANGe UPPer lt n gt Set measurement range for O Command Parameter lt n gt 0 to 20e6 Expected reading is ohms DEFault 20e6 Q MINimum 0 All functions MAXimum Same as DEFault Query RANGe UPPer Query measurement range of the current function Description This command is used to manually select the measurement range for the specified measurement function The range is selected by specifying the expected reading as an absolute value The instrument will then go to the most sensitive range that will accommodate that expected reading For example if you expect a reading of approximately 500 simply let the parameter n 50 in order to select the 5000 range AUTO b Command syntax RESistance RANGe AUTO b Set auto range for O Command parameter lt b gt 10rON Enable auto range 0 or OFF Disable auto range Query AUTO Query
23. or disable HOLD OFF STATe Query state of HOLD HOLD Command The following commands are used to configure and control the HOLD feature WINDow lt NRf gt Command syntax HOLD WINDow lt NRf gt Command Parameter lt NRf gt 0 01 to 10 Set window percent Query WINDow Query Hold window Description This command is used to set the window for HOLD This window is expressed as a percent of the seed reading for the Hold process COUNt lt NRf gt Command syntax HOLD COUNIt lt NRf gt Command Parameter lt NRf gt 2to100 Specify HOLD count Query COUNt Query HOLD count Descripton This command is used to specify the count for HOLD COUNt is the number of readings that are compared to the seed reading during the HOLD process STATe b Command syntax HOLD STATe lt b gt Command Parameter lt b gt OorOFF Disable HOLD 1 or ON Enable HOLD Query STATe Query state of HOLD Description This command is used to enable or disable HOLD 6 3 8 TRIGger subsystem These commands in this subsystem are used to configure and control trigger measurement function and are summarized in Table 6 8 Table 6 8 TRIGger Subsystem Commands Summary Command Function Description Default TRIGger SOURce lt name gt Select control source IMMediate SOURce Query control source TRIGger TRIGger subsystem commands are used for the instrument settings of trigger mode trigger
24. ssc nce ctw a E E A 25 3 8 Measuring True RMS AC DC sissies rrr ce eanna E EE EENE EEE TSE E IKEE EEEREN OTTE DE ESTS 26 orm COMEC 1c MN ctore 26 3 8 2 Using the 2 parameter displaced tm citm te ts oett theca 27 3 0 Math EuBCUODS esercita vt aa a A a ARCU EEUU UU ER RR ATO aa tunes EE caeven VERE FEE TEE UC REPE e VAS UMS 27 RENI m M 27 3 9 2 dB 1 ACU ALON Mp 28 39 8 dBm CAC Ul ALON e S 29 clem Ascccumpgdsee M 31 4 1 Measurement configuration uento heri ar oe aer td en tee ee eo ee eee ee 31 4 od be t Lao mene peepee etree re rye tutu tmd UE E EE 31 LXBAMIuum 32 AN OS dw t EE 32 42 THE SER Operations oris se niaes ona er Ea A AETA EE TAE EENES esesusvsaes vasteeties FONTE QUE Yo SAS EEIEIEE SNE 33 42A Tigger OW enun a a a a EEA 33 4 2 2 Reading Holderness E a e E E REN 34 A3 E MON R A E E A QNS NISI INS E A E NNVE UIN EIUS 34 LE dO SCIT 35 4 4 1 Enabling MitS te ettet e e fette errors weeny ere vr e et este or etie ut rene ey 35 LESE IIDPEELIRECII 35 4 5 System OperatlQns iicet ee arde en Pn e EO P eR RN e FAR SURE D SEHR Ideen ERA egeta rope 36 SERE dro io MP 36 4 5 2 Baud Tale estu EIEI NE IPM II PIU IM NIINIM MISI MR CI IET 36 4 5 3 Selecting the Terminal Character iiir retreat beni im Reti ebe bete e eui tbe reed ue EH d eek va 37 454 Key SOUNA csse asi em den
25. the menu level A MATH MEU will be displayed 3 Press W to move down to the command level within the MATH MEU 4 Use 4 or B key to move across to the HIGH LIMIT command 1 HI LIMIT will be displayed 5 Press W to move down a level to input the high limit value The present high limit value will be displayed HI 1 00000 6 Use 4 and gt keys to choose a numerical place and use A and V keys to increment or decrement the digits Enter an expected value for high limit 7 Press ENTER to confirm the value of high limit The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command level 8 Use lt gt or B key to move across to the LOW LIMIT command 2 LO LIMIT will be displayed 9 Press W to move down a level to input the low limit value The present low limit value will be displayed LO 1 00000 10 Use lt gt and gt keys to choose a numerical place and use A andy keys to increment or decrement the digits Enter an expected value for low limit 11 Press ENTER to confirm the value of low limit The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command level 12 Press wit key to exit from the menu and return to the measurement status prese 4 5 System Operations Model TH1942 has some
26. 1000VDC or peak ac for all ranges AC Voltage Resolution Full Scale reading and Accuracy Range Resolution Full Scale Reading 500 00 mV 10 uV 510 00 5 0000 V 100 pV 5 1000 50 000 V 1 mV 51 000 500 00 V 1 0mV 510 00 750 0 V 100 mV 757 5 196 over range 757 50V is readable at 750V range ACCURACY x 96 of reading of range 23 C 5 C Accuracy 1 year 23 C 5 C Rate Range 20 50 Hz 50 20kHz 20 50kHz 50 100kHz 500 00mV 1 0 0 08 0 5 0 06 1 5 0 1 3 0 0 3 5 0000 V 1 0 0 08 0 35 40 02 1 0 04 3 0 0 1 Slow 50 000 V 1 0 0 08 0 35 40 02 1 0 04 3 0 0 1 500 00V 0 5 0 03 1 0 04 3 0 0 1 750 0V 0 5 0 03 1 0 04 3 0 0 1 Specifications are for SLOW rate and sinewave inputs gt 5 of range Limit at 40KHZ or lt 3x10 Volt Hz for t 750V range Measurement method True RMS measurement Maximum Crest factor 3 0 at full scale Maximum input voltage 750Vrms lt 3x10 Volt Hz for all ranges Input impedance 1MOQ 2 in parallel with capacitance lt 100pF Maximum DCV 500V for all AC ranges DC Current Full Scale Accuracy Burden Voltage Rate Range Resolution Reading 1 year amp Shunt Resistor 5 0000mA 0 1 pA 5 1000 0 05 0 01 2 0 6V 1000 50 000mA 1pA 51 000 0 05 0 008 0 06V 10 Slow 500 00mA 10pA 510 00 0 05 0 008 0 6V 10 5 0000 A 100A 5 1000 0 25 0 01 0 1V 10mQ 20 000A 1mA 21 000 0 25 0 01 0 6V 10
27. ATe Query state of reference Description These commands are used to enable or disable Reference for the specified function When enabled the displayed reading will include the programmed reference value When disabled the displayed reading will not include the reference value ACQuire Command syntax FREQuency REFerence ACQuire Acquire reference for FREQ PERiod REFerence ACQuire Acquire reference for PER Description When one of these commands is sent the measurement input signal is acquired and established as the reference value This command is typically used to zero the display For example if the instrument is displaying a 10HZ offset sending this command and enabling Reference zeroes the display This command is functional only if the instrument is on the specified measurement function Sending this command while in any other function causes an error Also if the latest reading is overflowed or a reading has not been triggered an error occurs when this command is sent 6 3 7 HOLD subsystem The commands in this subsystem are used to configure and control hold measurement function and are summarized in Table 6 7 Table 6 7 HOLD Subsystem Commands Summary Command Function Description Default HOLD Path to control Hold feature WINDow lt NRf gt Set Hold window 0 01 to 10 1 WINDow Query Hold window COUNt lt NRf gt Set Hold count 2 to 100 5 COUNt Query HOLD count STATe lt NRf gt Enable
28. I IN LO PASS FAIL Max Min Note The measurement range is determined by main measurement function when a 2 parameter is displayed 3 9 Math Functions Model TH1942 math operations are divided into four categories WB percent E dB and dBm calculations W Limit testing The first two categories are discussed here reading limit testing are described in the next chapter Measurement Options 3 9 1 Percent If the percent calculation is selected a reference value must be specified The displayed reading will be expressed as percent deviation from the reference value The percentage calculation is performed as follows Input reference Percent P i reference Where Input is the normal display reading Reference is the user entered constant Percent is the displayed result To configure the percent calculation perform the following steps 1 Press shit Ra for percent math operation and the present reference value displays 1 00000 Use 4 and gt keys to choose a numerical place and use A and VV keys to increment or decrement the digits Enter a value and units prefix Press ENTER to confirm the reference value The message SAVED will be displayed for a moment TH1942 will display the result of the percent calculation If you want to change the parameter values when the percent math function is enabled besides the foregoing method you can take actions as below 1 2
29. ON or OFF Description These command are used to control auto ranging With auto ranging enabled the instrument automatically goes to the most sensitive range to perform the measurement The auto range command RANGe AUTO is coupled to the command that manually selects the measurement range RANGe n When auto range is enabled the parameter value for RANGe n changes to the automatically selected range value Thus when auto range is disabled the instrument remains at the automatically selected range When a valid RANGe n command is sent auto ranging disables REFerence n Commands REFerence lt n gt Command syntax VOLTage AC REFerence n VOLTage DC REFerence n Command parameter lt n gt 757 5 to 757 5 1010 to 1010 DEFault MINimum MAXimum Query REFerence Descripton Specify reference for ACV Specify reference for DCV Reference for ACV Reference for DCV 0 All measurement functions Mininum value for specified function Maximum value for specified function Query reference for relative function These commands are used to establish a reference value for the specified function When reference is enabled REFerence STATe the result will be the algebraic difference between the input signal and the reference value Reading Input signal Reference From the front panel reference is called relative REL The REFerence n command is coupled to the ACQuire command
30. OPERATION MANUAL TH1942 50000 Count Multimeter Changzhou Tonghui Electronic Co Ltd www tonghui com cn Manual Printing History The manual printing data and part number indicate its current edition The printing date changes when a new edition is printed The manual part number changes when extensive technical changes are incorporated October 2008 eitis First Edition Notice The information contained in this document is subject to change without notice oafety notice supplement As described in the International Electrotechnical Commission IEC Standard IEC 664 digital multimeter measuring circuits e g Tonghui Models 1951 1961 1941 and 1942 are Installation Category II All other instruments signal terminals are Installation Category and must not be connected to mains This equipment is POLLUTION DEGREE 2 INDOOR USE product Safety Precautions Users of this product must be protected from electric shock at all times The responsible body must ensure that users are prevented access and or insulated from every connection point In some cases connections must be exposed to potential human contact Product users in these circumstances must be trained to protect themselves from the risk of electric shock If the circuit is capable of operating at or above 1000 volts no conductive part of the circuit may be exposed Before operating an instrument make sure the line cord is connected to a properly grounde
31. a higher range until an on range reading is displayed Use the lowest range possible without causing an overflow to ensure best accuracy and resolution Auto ranging To enable auto ranging press key The AUTO annunciator turns on when auto ranging is selected While auto ranging is selected the instrument automatically chooses the best range to measure the applied signal However auto ranging should not be used when optimum speed is required 2a 1s Note that up ranging and down ranging occurs at 5 of normal range To cancel auto ranging press or amp orl V key Pressing to cancel auto ranging leaves the instrument on the present range The key has no effect on the continuity and diode test functions 4 1 2 Relative The relative operation could be used to null offsets or subtract a baseline reading from present and future readings When relative function is enabled Model TH1942 uses the present reading as a relative value Subsequent readings will be the difference between the actual input value and the relative value You can define a relative value for each function Once a relative value is set for a measurement function the value is the same for all ranges For example if 2V is set as a relative value on the 50V range the relative is also 2V on the 1000V 500V 5V or 500mV ranges Additionally when you perform a zero correction for DCV O measurements by enabling REL the displayed offset becomes the reference value Sub
32. a relative value is in effect when dB is selected the value is converted to dB then REL is applied to dB If REL is applied after dB has been selected dB has REL applied to it To set the reference voltage perform the following steps 1 Press sit 4 for dB math operation and the present reference value is displayed R F 0 00000 2 Use 4 and gt keys to choose a numerical place and use A ady keys to increment or decrement the digits Enter a value and units prefix 3 Press ENTER to confirm the reference voltage the message SAVED will be displayed for a moment TH1942 returns back to the measurement status 4 TH1942 will display the result of the dB calculation If you want to change the parameter values when dB function is in effect you can take actions as below 1 Press st Es lt to enter the menu on the menu level A MATH MEU will be displayed 2 Press W to move down to the command level within the MATH MEU 4 dB REF will be displayed 3 Press V to enter the parameter level and the present reference value will be displayed R F 1 00000r 4 Usef 4 and gt keys to choose a numerical place and use A ady keys to increment or decrement the digits Enter a value and units prefix 5 Press ENTER to confirm the reference value the message SAVED will be displayed for a moment and TH1942 will return to the command level Press to cancel the reference value input TH1942 returns back
33. a separator to execute multiple commands on a single line The multiple command rules are as follows Commands at the same level and in the same subsystem command group can be separated by a semicolon on a multiple command line For example RESistance NPLCycle n NPLCycles To restart commands from the highest level a semicolon must be used as the separator and then a leading colon which shows that the restarted command is a command at the top of the command tree must follow For example RESistance NPLOycle n RESistance NPLCycles The GPIB common commands can restart only after a semicolon on a multiple command line For example RESistance NPLOycles n IDN 6 2 5 Command Path Rules Each new program message must begin with the root command unless it is optional e g FUNCtion If the root is optional simply treat a command word on the next level as the root The colon at the beginning of a program message is optional and need not be used Example DISPlay ENABle lt b gt DISPlay ENABle lt b gt When the path pointer detects a colon it moves down to the next command level When the path pointer detects a colon after a semicolon it resets back to the root level The path pointer can only move down It cannot be moved up a level Executing a command at a higher level requires that you start over at the root command 6 3 Command Reference Model TH1942 provides foll
34. ar 500 000 10mQ 510 00 0 5 mA 0 10 0 01 5 0000 kQ 100mQ 5 1000 0 45 mA 0 10 0 008 50 000kQ 10 51 000 45A 0 10 0 008 Slow 500 00kQ 100 510 00 4 5UA 0 10 0 008 5 0000MQ 1000 5 1000 450nA 0 15 0 008 50 000MQ 1kQ 51 000 45nA 0 3 0 01 In order to eliminate the noise interference which might be induced to the test leads it is recommended to use a shielded test cable for measuring resistance above 100kQ Using REL function Maximum Input Protection 1000VDC or 750VAC for all ranges Open circuit voltage Maximum voltage is 5 5V dc Continuity Full Scale Accuracy 1 year R Resolut Test C t ange esolution Reading est Curren 23 C 5 C 5000 100mQ 999 9 0 5mA 0 1 0 04 Maximum Input Protection 1000VDC or 750VAC for all ranges Open circuit voltage lt 5 5V DC Test Current around 0 5 mA DC Threshold value 2 of range Diode Full Scale Rate Range Resolution f Test Current Reading Med 2 0000V 100V 2 3000V 0 5mA Frequency ACV Frequenc Full Scale Input Sensitivit 3 Y Resolution Accuracy P y Range Range Reading Sine Wave 100m 5 10 Hz 100u0Hz 9 9999 0 05 0 02 200mV rms i 10 100Hz 1mHz 99 999 0 01 0 02 300mV rms 750V 100 100 kHz 10m Hz 999 99 0 01 0 008 300mV rms 100k 1MHz 10Hz 999 99 0 01 0 008 500mV rms Period ACV Frequency Resolution Full pene Accuracy put S
35. ation function selecting keys Select a 2 display parameter Select a 2 display parameter gt f ow L lt val ERG Select a higher range and disable auto ranging Select a lower range and disable auto ranging Toggle between auto ranging and manual ranging Trig Hold Key Tig Trigger a measurement from the front panel Shift Ti Hold a stable reading on the display when selected numbers of samples are within the selected tolerance Shift Local keys Shirt Used to access shifted keys Shift LOCAL Cancel RS232C remote control mode and back to the LOCAL mode Annunciators on Screen 2 2 FAST MED SLOW TRIG HOLD REL MATH gt Speaker Diode DC AC COMP HI IN LO RMT AUTO Max Min ERR SHIFT FAST MED SLOW TRIG HOLD AUTO REL MATH pis mp PT a UL AC DC COMP HI LO RMT AUTO MAX MIN BRR SHIFT Figure 2 2 Display Annunciators Fast reading rate Medium reading rate Slow reading rate Indicates external trigger front panel bus selected Reading HOLD function is enabled Relative reading displayed A math operation is enabled 96 dB dBm Beeper on for continuity testing function Instrument is in diode testing function DC operation is enabled AC operation is enabled Limit testing function is enabled Indicates the limit testing results Multimeter is in remote control mode Auto ranging enabled MAX MIN operation is enabled Hardware or remote c
36. auto range ON or OFF Description These commands are used to control auto ranging With auto ranging enabled the instrument automatically goes to the most sensitive range to perform the measurement The auto range command RANGe AUTO is coupled to the command that manually selects the measurement range RANGe lt n gt When auto range is enabled the parameter value for RANGe n changes to the automatically selected range value Thus when auto range is disabled the instrument remains at the automatically selected range When a valid RANGe n command is sent auto ranging disables REFerence n Commands REFerence n Command syntax RESistance REFerence n Specify reference for O Command parameter lt n gt 0 to 20e6 Reference for Q DEFault 923107715guozhigang 0 All measurement functions MINimum Mininum value for specified function MAXimum Maximum value for specified function Query REFerence Query reference for relative function Descripton These commands are used to establish a reference value for the specified function When reference is enabled REFerence STATe the result will be the algebraic difference between the input signal and the reference value Reading Input signal Reference From the front panel reference is called relative REL The REFerence n command is coupled to the ACQuire command The last command sent REFerence n or ACQuire eatablishes the reference When a
37. bem PUR E Rn EU o Rt rS RE OMM ritus tua aee EEE R nM oin HEN E 37 ASIA iciPsmui is 6 o jr iio MM M EEEE Ne 39 xm ooi ETE eras tft es ere vate stv onic sana ona 39 5 2 RS 232 Interface Operations i t tern teet et E NEE ANSES EEA NENEA SESER Niet 39 5 2 1 RS 232 CONME resensies aerae iaeia TE tru TR ERR EE a Enae 39 5 2 2 Sending and receiving datas canvnasscansnepaeonp nasa encinstiemyneldeassanta amsenis nian uses eaniss i euse isii sisiran 40 5 2 3 Selecting Baud Rate MEE mo o UT 41 5 2 4 SoftWare PIDIOGOL ui pi bip REDI UE DUNS RIS IL REN EUR MUN E NEM IU RUE IM UND N E 4l RES Data POrnMa t E 42 Chapter 6 SCPI Command PelerSnoB soin oito Rap akt xin erdt ab qu us bo feu ipe Du fabu pies 43 6 T Command SUUct te ero ece trretoct teato lat E dev Dex bee ee dene maed eS ee ERU ER ed 43 6 2 Command Syntax eei iiti tein ed ERR RR ERR E ERREUR HER RUE RE ERR ERE ERR AERE ERR ENORET HERR AR eina 43 6 2 1 Commands and command palamelers siuse sov ARR RYE REN EXP CAVO REEL RR e VEN PAURA EIER E 43 6 2 2 c aime RUES MNT C ETENN EEEN 45 6 2 3 Basic Rules of Command Structure sss rer tho tr RP SEE PRIMER LUE s heures GM tn dsbaEU CA 45 6 2 4 Multiple Command Rules ioter etes estt o br Ebert EP eee tres ntn PE Vibe Eee e TP Ipse rona eR ELE 46 6 2 5 Command Path PUB aci issr te ut pb nip israse ortos ioa PUE tonsa truc ug RE PS UR nu DE DERE 46 6 3 Command Reference 4 iiic te d n t e rr Hte Poet
38. d power receptacle Inspect the connecting cables test leads and jumpers for possible wear cracks or breaks before each use For maximum safety do not touch the product test cables or any other instruments while power is applied to the circuit under test ALWAYS remove power from the entire test system and discharge any capacitors before connecting or disconnecting cables or jumpers or making internal changes such as installing or removing jumpers Do not touch any object that could provide a current path to the common side of the circuit under test or power line earth ground Always make measurements with dry hands while standing on a dry insulated surface capable of withstanding the voltage being measured The instrument and accessories must be used in accordance with its specifications and operating instructions or the safety of the equipment may be impaired Do not exceed the maximum signal levels of the instruments and accessories as defined in the specifications and operating information and as shown on the instrument or test fixture panels When fuses are used in a product replace with the same type and rating for continued protection against fire hazard Chassis connections must only be used as shield connections for measuring circuits NOT as safety earth ground connections If you are using a test fixture keep the lid closed while power is applied to the device under test Contents Chapter 1 SMS
39. delay and trigger a measurement SOURce lt name gt Command Syntax TRIGger SOURce lt name gt Command parameter lt name gt IMMediate instrument default setting is internal trigger BUS Triggered via RS232 interface MANual EXTernal Press tris in the front panel for Trigger Query SOURce Query control source Description These are used to select the event control source 6 3 9 FETCH Subsystem FETCh Command Command syntax FETCh Description This query command is used to obtain the lastest post processed reading This command does not affect the configuration of the instrument This command does not trigger a measurement The command simply requests the last available reading This command continues to return the same old reading until there is a new reading This command will be automatically asserted when READ or MEASure command is sent 6 3 10 Common Commands Common commands can be used to all equipments We provide some common commands as below RST Command Syntax RST Description Reset the instrument TRG Command Syntax TRG Description Trigger the instrument for measurement IDN Query Syntax IDN Query return product version LF END Here product TH1942 Digital Multimeter version Ver1 0 Description Query information returned to instrument Chapter 7 Specifications A 1 Introduction Chapter 7 describes the complete specifications o
40. ement input signal is acquired and established as the reference value This command is typically used to zero the display For example if the instrument is displaying a 10pA offset sending this command and enabling Reference zeroes the display This command is functional only if the instrument is on the specified measurement function Sending this command while in any other function causes an error Also if the latest reading is overflowed or a reading has not been triggered an error occurs when this command is sent 6 3 5 RESlister subsystem The commands in this subsystem are used to configure and control resistance measurement function and are summarized in Table 6 5 Table 6 5 RESIister Subsystem Commands Summary Command Function Description Default RESistance Path to configure resistance NPLOycles lt n gt Set integration rate line cycles 0 5 to 2 1 NPL Cycles Query line cycle integration rate RANGe Path to configure measurement range UPPer n Select range 0 to20e6 20e6 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence lt n gt Specify reference 0 to 2066 0 STATe b Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value Speed Commands NPLCycles lt n gt Command Systac RESistance NPL Cycles lt n gt Set NPLC for Q Command Parameter
41. ensitive current or voltage threshold range REFerence n Commands REFerence lt n gt Command syntax FREQuency REFerence n Specify reference for FREQ PERiod REFerence lt n gt Specify reference for PER Command parameter n 0 to 1 0e6 Reference for FREQ 0 to 1 Reference for PER DEFault 0 All measurement functions MINimum Mininum value for specified function MAXimum Maximum value for specified function Query REFerence Query reference for relative function Descripton These commands are used to establish a reference value for the specified function When reference is enabled REFerence STATe the result will be the algebraic difference between the input signal and the reference value Reading Input signal Reference From the front panel reference is called relative REL The REFerence n command is coupled to the ACQuire command The last command sent REFerence n or ACQuire eatablishes the reference When a reference is set using the REFerence n command the REFerence Query command returns the programmed value Conversely when a reference is set using the ACQuiry command the REFerence Query command returns the acquired reference value STATe b Command syntax FREQuency REFerence STATe lt b gt Control reference for FREQ PERiod REFerence STATe b Control reference for PER Command parameter lt b gt 1orON Enable reference 0 or OFF Disable reference Query ST
42. ensitivity Range Range Reading Sine Wave anu 1 10us 0 1ns 9 9999 0 01 0 008 500mV rms io 10us 10ms ins 9 9999 0 01 0 008 300mV rms 750V 10ms 100ms 1us 99 999 0 01 0 02 300mV rms 100ms 200ms 10us 199 99 0 05 0 02 200mV rms Maximum Crest factor 3 0 at full scale Maximum input voltage 750Vrms lt 3x10 Volt Hz for all ranges Input impedance 1MOQ 2 in parallel with capacitance 100pF Maximum DCV 500V for all AC ranges Triggering and Memory Reading hold sensitivity 0 01 0 1 1 or 10 of reading Math Functions Rel Max Min dBm dB Compare Limit Test and dBm Reference Resistance 10 to 99990 10 step size default is 750 Standard Programming Languages SCPI Standard Commands for Programmable Instruments Remote Interface GPIB IEEE 488 2 and RS 232C General Specifications Power Supply 110 220V 10 Power Line Frequency 50 60Hz 5 Power Consumption lt 10VA Operating Environment 0 C to 40 C lt 90 RH Storage Environment 40 C to 70 C Warm up more than 30mins Dimensions WxHxD 225mmx100mmx355mm Net Weight Around 2 5Kg Warranty 2 years Chapter 8 Program Examples Serial Interface Program The following example is a communication program It is programmed with C Language and working in DOS environment Where the MAIN Function could be extended for communication functions by users and other sub functions show you how to input and output character strings using
43. er level commands and the lower level commands See Figure 6 1 for a sample p nn RESistance RANGe STATe SENS RES RANG 1k SENS HOLD STAT ON AUTO SENS RES RANG AUTO ON Figure 6 1 Command Tree Example 6 2 Command Syntax The information in this section covers the syntax for both common commands and SCPI commands 6 2 1 Commands and command parameters Common commands and SCPI commands may or may not use a parameter The following are some examples RST No parameter used FORMat name Parameter lt name gt required IMMediate No parameter used Put at least one space between the command word and the parameter Brackets Some command words are enclosed in brackets These brackets are used to denote an optional command word that does not need to be included in the program message For example RANGe UPPer n These brackets indicate that UPPer is optional and does not have to be used Thus the above command can be sent in one of the two ways below RANGe n or RANGe UPPer n NOTICE When using optional command words in your program do not include the brackets Angel brackets Angle brackets are used to denote a parameter type Do not include the brackets in the program message For example HOLD STATe lt b gt The b indicates that a Boolean type parameter is required Thus to enable the HOLD feature yo
44. et integration rate line cycle 0 5 to 2 1 NPL Cycles Query line cycle integration rate RANGe Path to configure measurement range UPPer n Select range 0 to 1010 1000 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence n Specify reference 1010 to 1010 0 STATe b Enable or disable reference OFF STATe Query state of reference 0 1 ACQuire Use input signal as reference REFerence Query reference value VOLTage AC Path to configure AC voltage NPL Cycles lt n gt Set integration rate line cycles 0 5 to 2 1 NPL Cycles Query line cycle integration rate RANGe Path to set measurement range UPPer n Select range 0 to 757 5 757 5 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence n specify reference 757 5 to 757 5 0 STATe b Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value Speed Commands NPLCycles lt n gt Command Systac VOLTage AC NPLOycles n VOLTage DC NPL Cycles lt n gt Set NPLC for ACV Set NPLC for DCV Command Parameter n 0 5102 Set power line cycles per integration DEFault 1 MINimum 0 5 MAXimum 2 Query NPLCycles Query programmed NPLC value Description The integration period measurement speed for the basic measurement functions
45. f the Model TH1942 Multimeter A 2 Technical Specifications Specifications Assumptions One year calibration cycle Operating temperature at 18 C to 28 C Accuracy is expressed as of reading digits after 30 minutes warm up Temperature Coefficient add 0 1 x the applicable accuracy C for 0 C to 18 C and 28 C to 40 C m Relative Humidity Up to 80 for 0 C to 28 C 75 RH for 10MO and above ranges of resistance measurement Up to 70 for 28 C to 40 C Displayed Readings and Reading rates Reading rates on front panel Reading sec Approximate Measurement Function Slow Med Fast DCV 5 10 25 DCA 5 10 25 ACV 5 10 25 ACA 5 10 25 Q Ranges below 5M 5 10 25 Q 50M range and above 1 3 2 6 5 6 Freq Period 1 2 3 9 Using dual display 0 9 0 9 0 8 True RMS DC AC 1 2 1 4 1 5 Diode 10 Continuity 25 DC Voltage Resolution Full Scale reading and Accuracy Full Scale Accuracy Typical Rate Range Resolution Input Reading 1 year Impedance 500 00mV 1 0V 510 00 0 02 0 016 gt 10MQ 5 0000 V 100ygV 5 1000 0 02 0 008 gt 11 1MQ Slow 50 000V 1mV 51 000 0 02 0 008 gt 10 1MQO 500 00 V 10 mV 510 00 0 02 0 008 10MO 1000 0 V 100 mV 1010 0 0 02 0 008 10MO under REL status 196 over range 1010V is readable at 1000V range Maximum input voltage
46. face 5 2 1 RS 232 Connection RS232C standard now is widely used as the serial communication standard RS232 stands for Recommend Standard number 232 and C is the latest revision of the standard The serial ports on most instruments use a subset of the RS232C standard The full RS232C standard specifies a 25 pin D connector of which 22 pins are used Most of these pins are not needed for normal serial communications and the common RS232 signals are listed in Table 5 1 Table 5 1 Signal Definition for 9 Pin Connector 9 Pin Connector Function Code piniNumber Request To Send RTS 7 Clear To Send CTS 8 Data Set Ready DSR 6 Data Carrier Detect DCD 1 Data Terminal Ready DTR 4 Transmitted Data TXD 3 Received Data RXD 2 Signal Ground Common GND 5 4 TH1942 s serial port uses the transmit TXD receive RXD and signal ground GND lines of the RS232 standard It does not use the hardware handshaking lines CTS and RTS TH1942 only uses the smallest subset of the RS232C standard the signal are listed in Table 5 2 Table 5 2 Signal Definition for 9 Pin Connector Function Code 9 Pin Connector Pin Number Transmitted Data TXD 3 Received Data RXD 2 Signal Ground Common GND 5 Figure 5 1 shows the rear panel connector for the RS232 interface 12345 W 6789 RS232 Figure 5 1 Rear
47. ffect TH1942 will exit the parameter level and move up a level to the command level 8 Press shin key to exit from the menu and return to the measurement status 4 5 3 Selecting the Terminal Character The instrument has two kinds of terminal characters lt LF gt and lt CR gt Perform the following steps to select the terminal characters 1 Press si 4 to enter the menu on the menu level A MATH MEU will be displayed 2 Use 4 o gt key to move across to the SYS MENU on the menu level C SYS MEU will be displayed 3 Press W to move down to the command level within the SYS MEU 1 BEEP STR will be displayed 4 Usel 4 o gt key to move across to the terminal character command 3 TX TERM will be displayed 5 Press W to move down a level to set the terminal character 6 Usel 4 or gt key to select a terminal character 7 Press ENTER to confirm the selection The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command level 8 Press t key to exit from the menu and return to the measurement status 4 5 4 Key Sound To avoid mis operation Model TH1942 has key sound function and you can enable or disable it Factory default setting is enabled The key sound state is stored in non volatile memory and does not change when power has been off of after a reset Use following steps for key sou
48. he following warning When making measurements in high energy circuits use test leads and accessories that meet the following requirements M Test leads and accessories must be fully insulated B Only use test leads that can be connected to the circuit e g alligator clips spade lugs etc for hands off measurements m Do not use test leads or accessories that decrease voltage spacing This diminishes arc protection and creates a hazardous condition Use the following sequence when measuring high energy circuits 1 De energize the circuit using the regular installed connect disconnect device such as a circuit breaker main switch etc 2 Attach the test leads to the circuit under test Use appropriate safety rated test leads for this application 3 Setthe multimeter to the proper measurement function and range 4 Energize the circuit using the installed connect disconnect device and make measurements without disconnecting the multimeter 5 De energize the circuit using the installed connect disconnect device 6 Disconnect the test leads from the circuit under test WARNING The maximum common mode voltage vollage between COM and the chassis ground is 500V peak Exceeding this value may cause a breakdown in insulation creating a shock hazard 2 2 6 5 Power on Defaults Model TH1942 uses the factory default settings for the power on settings Since the basic measurement procedures in this manual assume the facto
49. his chapter is organized as follows m Measurement Configuration Describes Ranging Relative readings Digits of Resolution and Measurement rate Triggering operations Explains trigger sources MAX and MIN operations Records the minimum and the maximum input signals Limit operations Defines how to set reading limits System Operations Provides details on Beep setup Baud rate setup Terminal character setup and key sound setup 4 1 Measurement configuration The following paragraphs discuss configuring multimeter for making measurement 4 1 1 Range You can let the multimeter automatically select the range using auto ranging or you can select a fixed range using manual ranging Auto ranging is convenient because the multimeter automatically selects the appropriate range for each measurement However you can use manual ranging for faster measurements since the multimeter doesn t have to determine which ranging to use for each measurement The multimeter returns back to auto ranging when power has been off or after a remote interface reset Maximum readings The full scale readings for every range on each function are 5 over range except for the 1000VDC 750VAC and diode test ranges Manual ranging To select a range simply press A or V key The instrument changes one range per key press The selected range is displayed for a moment If the instrument displays the OVL D message on a particular range select
50. igure 2 5 The multimeter is protected against overloads up to the limits shown in Table 2 1 Exceeding these limits may result in a hazard to both the meter and operator 5mA 500mA range DC AC current input terminals for DC AC current measurements Input High terminal for Volts ohms HZ period diode and continuity measurements Common terminals 5AA 0A range current input terminal for DC AC current measurement 5mA 500mA range fuse T1AL 250V TIAL 250V ALL INPUT 1KV MAX S Figure 2 5 Input terminals 2 Table 2 1 Input protection Limits Function Input Terminals Maximum Allowable Input DCV VO to COM 1010V DC ACV HZ VOX to COM 757 5V AC RMS 1000V Peak mA HZ 500mA to COM 500mA DC or AC RMS 20A HZ 20A to COM 20A DC or AC RMS Q VQ to COM 500V DC or AC RMS gt VQ to COM 500V DC or AC RMS All functions Any terminals to earth 1000V DC or 1000V peak AC 2 6 3 Power up Sequence On power up Model TH1942 performs self tests on its EPROM and RAM and lights all segments and annunciators for about 1 second If a failure is detected the instrument momentarily displays an error message and the ERR annunciator turns on If the instrument passes self tests the firmware revision will be displayed 2 6 4 High Energy Circuit Safety Precautions To optimize safety when measuring voltage in high energy distribution circuits read and use the directions in t
51. ion 220V 500mA or 110V 1A Note Please use the same type fuse or contact your nearest Tonghui sales and service office To verify and replace the fuse remove the power cable and pull out the fuse holder 4 Label Serial number for this instrument 2 6 Power up 2 6 1 Power Line Connection Follow the procedure below to connect the TH1942 to line power and turn on the instrument 1 Check to make sure that the line voltage is in the range of 198V to 242V or 110V 10 and line frequency is in the range of 47 5 to 52 5Hz or 60Hz 5 before connecting the power cord CAUTION Operating the instrument on an incorrect voltage may cause damage to the instrument possibly voiding the warranty 2 Before plugging in the power cord make sure that the front panel power switch is in the off position 3 Connect the female end of the supplied power cord to the AC receptacle on the rear panel Connect the other end of the power cord to a grounded AC outlet WARNING The power cord supplied with the Model TH1942 contains a separate ground wire for use with grounded outlets When proper connections are made instrument chassis is connected to power line ground through the ground wire in the power cord Failure to use a grounded outlet may result in personal injury or death due to electric shock 4 Turn on the instrument by pressing the front panel power switch and get ready for measuring 2 6 2 Input Terminals The input terminals are shown in F
52. ital multimeter with high accuracy stability and speed The multimeter can provides a maximum measurement speed of 25 readings sec TH1942 has 0 01 DC voltage basic accuracy 0 0396 basic resistance accuracy and other high performance TH1942 has broad measurement ranges DC voltage from 10uV to 1000V AC RMS voltage from 10uV to 750V 1000V Peak DC current from 100nA to 20A AC RMS current from 100nA to 20A Two and four wire resistance from 10mQ to 50MO Frequency from 5Hz to 1MHz Some additional capabilities of Model TH1942 1 2 Full range of functions In addition to those listed above The TH1942 functions include period dB dBm continuity diode testing max min and percent Programming languages and remote control interfaces The TH1942 provides the SCPI programming language and the remote control interface port RS 232C Closed cover calibration The multimeter can be calibrated either from the front panel or remote interface Operating Environment Power supply 110V 220V 10 Line frequency 50Hz 60Hz 5 Power consumption 10VA Operating temperature 0 C to 40 C Humidity lt 90 RH 1 3 Dimensions and Weight Dimensions WxHxD 225mmx100mmx318mm Net weight Around 2 2Kg 1 4 Safety symbols and Precautions The A symbol on the instrument indicates that user should refer to the operating instructions located in the manual before performing The A symbol on the instrument shows that high voltage may
53. key to select ON or OFF Press ENTER to confirm the beeper control The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command level 8 Press 9 key to exit from the menu and return to the measurement status 4 5 2 Baud rate The baud rate is the rate at which Model TH1942 digital multimeter and the computer communicate Choose one of these available rates W 38 4k 19 2k 9600 4800 2400 1200 600 Note Factory default baud rate is 9600 NO oR Before you choose a baud rate make sure the programming terminal that you are connecting to the TH1942 can support the baud rate you selected Both the digital multimeter and the other device must be configured for the same baud rate Perform the following steps to select a baud rate 1 Press suit to enter the menu on the menu level A MATH MEU will be displayed 2 Usel lt or B key to move across to the SYS MEU on the menu level C SYS MEU will be displayed 3 Press V to move down to the command level within the SYS MEU 1 BEEP STR will be displayed 4 Usel 4 or B key to move across to the baud rate command 2 BAUD RAT will be displayed 5 Press W to move down a level to set the baud rate 6 Usel 4 o gt key to select a baud rate 7 Press ENTER to confirm the selection The message SAVED will be displayed to show that the change is now in e
54. l 13 Press Sit _ key to exit from the menu and return to the measurement status ONO 4 3 MAX MIN MAX MIN function enables TH1942 to record the minimum and the maximum readings If MAX MIN function is enabled the 2 display parameter indicates the latest maximum or minimum reading Use the following procedure to turn on the turn on the MAX MIN operation 1 Press to enable the MAX MIN function 2 Usel 4 orf P key to cycled view the maximum reading and minimum reading 3 Press key to exit from the menu 2 4 4 Limit Operations Limit operations set and control the values that determine the HI IN LO status of subsequent measurements Limits can be applied to all measurement functions except continuity The limit test is performed after percent math operations Unit prefixes are applied before the limit test for example Low Limit 1 0 High Limit 1 0 A 150mV reading equals 0 15V IN Low Limit 1 0 High Limit 1 0 A 0 6kO reading equals 6000 HI You can configure the multimeter to beep or not when readings are outside of the limit range 4 4 1 Enabling limits Use the following procedure to turn on the limit operation 1 Press shit to enter or exit the set of LIMIT TEST function 4 4 2 Setting Limit Values Use the following steps to enter high and low limit values 1 Press sit to enter the menu on the menu level 2 Use 4 or key to move across to the MATH MEU on
55. layed with auto ranging If you want manual ranging use the RANGE A ady keys to select a measurement range consistent with expected resistance Connect test leads to the resistance as shown in Figure 3 3 CAUTION Do not apply more than 1000V peak between V Q and COM or instrument damage AL am EN x VN NV may occur If the OVL D message is displayed press up A key to select a higher range until a normal reading is displayed or press key for auto ranging Use the lowest possible range for the best resolution Take readings from the display f f t tf ff E z DO AC En O Tang TH1942 50000 count Multimeter pov Gev ASAT aon Lj MB AUTO n Period paea HTRREIMPHM Ca ED aa LILIE LH IFT E dB dBm MAX Comp Rel Wax Min Jmm ZA 2nd Hold GQ E j Rate Trig if Acc gt S D Nen Local Ol COG EE e ae 9 se S aed POWER RESISTANCE C 7 q J A m d Note Source current flows from the VQ to COM terminals Figure 3 3 Resistance Measurements 3 4 2 Shielding To achieve a stable reading it helps to shield resistances greater than 100kQ Place the resistance in a shielded enclosure and connect the shield to the COM terminal of the instrument electrically Ste qx 3 5 Measuring Freque
56. mQ Typical voltage across the input terminals at full scale reading Use REL function 9 n 20A range gt 10 20Adc is readable for 20 seconds maximum Maximum Input and Overload Current Protection 1A 250V fuse AC Current True RMS AC Coupling Full Scale Burden Voltage Rate Range Resolution j Reading shunt Resistor 5 0000mA 0 1 uA 5 1000 0 6V 1000 50 000 mA 10pA 51 000 0 06V 10 Slow 500 00mA 100 pA 510 00 0 6V 10 5 0000A 1mA 5 1000 0 1V 10mO 20 000A 10mA 21 000 0 6V 10mO Typical voltage across the input terminals at full scale reading 9 n 20A range gt 10 20Aac is readable for 20 seconds maximum ACCURACY 96 of reading of range 23 C 5 C Accuracy 1 year 23 C 5 C Rate Range 20 50 Hz 50 2kHz 2 20kHz 5 0000mA 1 5 0 16 0 5 0 08 2 0 16 50 000 mA 1 5 0 16 0 5 0 08 2 0 12 Slow 500 00m A 1 5 0 16 0 5 0 08 2 0 12 5 0000A 2 0 0 16 0 5 0 1 20 000A 2 0 0 16 0 5 0 1 Specifications are for SLOW rate and sinewave inputs gt 5 of range In 20A range gt 10 20Aac is readable for 20 seconds maximum Measurement method True RMS measurement Maximum Crest factor 3 0 at full scale Maximum Input and Overload Current Protection 1A 250V fuse Resistance Rate Range Resolution iin nd Test Current RE Reading 1 ye
57. ncy and Period Model TH1942 frequency measurement range 5 Hz to more than 1MHz Model TH1942 period measurement range 0 2s to less than 1ys Input signal range 200 mV AC to 750V AC The instrument uses the volts input terminals to measure frequency The AC voltage range can be changed with the RANGE and V keys However the signal voltage must be greater than 1096 of the full scale range 3 5 1 Trigger Level and Measurement Errors Model TH1942 uses a technique which maintains a constant resolution for any input frequency to measure frequency and period The gate time is always a multiple of the measured signal period rather than a fixed time The error will be no more than 1 from the total gate counts this assures and equivalent accuracy over the whole frequency range 3 5 2 Gate Time Gate time is the amount of time Model TH1942 uses to sample frequency or period readings The measurement speed rate and the measuring frequency change the gate time 3 5 3 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is as follows 1 Connect test leads to V O 9 and COM terminals 2 Select frequency or period measurement functions by pressing Fa or shin Freq c 3 Connect test leads to the source as shown in Figure 3 4 CAUTION Do not exceed 1000V peak between VQ and COM or instrument damage may occur 4 Taking a reading from the display Il i
58. nd setting 1 Press shin to enter the menu on the menu level A MATH MEU will be displayed 2 Usel 4 o gt key to move across to the SYS MEU on the menu level C SYS MEU will be pre displayed Press W to move down to the command level within the SYS MEU 1 BEEP STR will be displayed Use 4 or gt key to move across to the KEY SONG command 4 KEY SONG will be displayed Press W to move down a level to enable or disable the key sound Use 4 or gt key to turn ON or turn OFF the key sound Press ENTER to confirm the selection The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command level Press key to exit from the menu and return to the measurement status Chapter 5 Remote Operation Besides the front panel control TH1942 supports RS 232 serial interface for remote control Standard Commands for Programmable Instruments SCPI is fully supported to communicated with computer by the RS 232 interfaces with a certain communication protocols 5 1 1 RS 232 You can connect RS 232 interface with a computer Some considerations will draw your attention m You must define the baud rate m You must use the SCPI programming language 5 2 RS 232 Interface Operation The instrument provides various remote commands All operations from the front panel can be performed by a computer via the RS 232 inter
59. nected correctly Check if the same baud rate is selected for both TH1942 and the controller When TH1942 is busy with executing a bus command TH1942 will not accept any character from the serial interface at the same time So the character sent by controller will be ignored In order to make sure the whole command is sent and received correctly the character without a return character should be sent again by the controller TH1942 only sends information under following two conditions The first is when a character is received normally TH1942 will send the character back as a handshake The second is when a query command is received TH1942 will send the query response information Once a query command is received TH1942 will send the query response information immediately even if the rest commands have not been finished So if the command includes two queries the controller should read the query responses twice One query is recommended to be included in a single command A query response is sent out in ASCII codes with the preset terminal character Several query responses will be sent continuously with 1ms interval The controller should be ready to receive the responses otherwise the response information will be lost The controller should receive the query response terminal character Otherwise you will confuse a terminal character with a returned character At the same time the controller should receive the last returned characte
60. ommand level 1 TRIG MOD will be displayed 5 Press W to move down a level to select a trigger source 6 Using lt gt or to select IMM MAN or BUS trigger source 7 Press ENTER to confirm the choice The message SAVED will be displayed to show that the change is now in effect TH1942 automatically exits the parameter level and moves up a level to the command level Measurement Sample The primary measurement sample action is a measurement However the measurement sample action block could include the following additional actions Hold with hold enabled the first processed reading becomes the Seed reading and operation loops back within the measurement sample block After the next reading is processed it is checked to see if it EE is within the selected window 0 01 0 196 1 and 10 of the seed reading If the reading is within the window operation again loops back within the measurement sample block This looping continues until the specified number 2 100 consecutive readings are within the winder If one of the readings is not within the window the instrument acquires a new seed reading and the hold process continues 4 2 2 Reading Hold When a hold reading is acquired as described in Measurement Sample an audible beep is sounded if enabled and the reading is considered a true measurement The reading is held on the display until an out of window reading occurs to restart the hold proce
61. ontrol error detected Accessing shifted keys 2 7 2 3 Front Panel Menu Reference A MATH MENU 1 HI LIMIT 2 LO LIMIT 3 PERC REF 4 dB REF 5 dBm REF 1 HILIMIT Set the high limit for limit testing 2 LOLIMIT Set the low limit for limit testing 3 PERC REF Set the reference value for PERCENT function 4 dB REF Set the dB reference voltage value 5 dBm REF Set the dBm reference impedance value B TRIGger MENU 1 TRIG MOD 2 HOLD WIN 3 HOLD CNT 1 TRIG MOD Select IMMediate Manual or Bus trigger source mode 2 HOLD WIN Set the reading hold sensitivity band 3 HOLD CNT COUNT of readings for reading hold C SYStem MENU 1 BEEP STA gt 2 BAUD RAT 3 TX TERM 4 KEY SONG 1 BEEP STA Enable or disable the beeper function 2 BAUD RAT Select the baud rate for RS232C operation 3 TX TERM Set the terminal character for RS232 operation which identifies the end of a Command string 4 KEY SONG Enable or disable the key sound when you press a key 2 4 Front Panel Menu Overview The menu is organized in a top down tree structure with three levels menus commands and parameters as shown in Figure 2 3 You can use down V or up to move menu tree from one level to another Each of the three levels has several horizontal choices which you can view by using let orrignt gt Menus Commands Parameters Figure 2 3 Menu Tree Toturn on the menu press
62. or example if you expect a reading of approximately 10mA simply let the parameter n 20 01 or 10e 3 in order to select the 20mA range AUTO lt b gt Command syntax CURRent AC RANGe AUTO lt b gt Set auto range for ACI CURRent DC RANGe AUTO lt b gt Set auto range for DCI Command parameter lt b gt 10rON Enable auto range 0 or OFF Disable auto range Query AUTO Query auto range ON or OFF Description These command are used to control auto ranging With auto ranging enabled the instrument automatically goes to the most sensitive range to perform the measurement The auto range command RANGe AUTO is coupled to the command that manually selects the measurement range RANGe lt n gt When auto range is enabled the parameter value for RANGe n changes to the automatically selected range value Thus when auto range is disabled the instrument remains at the automatically selected range When a valid RANGe n command is sent auto ranging disables REFerence n Commands REFerence lt n gt Command syntax CURRent AC REFerence n Specify reference for ACI CURRent DC REFerence lt n gt Specify reference for DCI Command parameter lt n gt 20to 20 Reference for ACI 0 to 20 Reference for DCI DEFault 0 All measurement functions MINimum Mininum value for specified function MAXimum Maximum value for specified function Query REFerence Query reference for relative function Descri
63. other operations Beeper control key sound control Baud rate control and Terminal character setup The information is not directly related to making measurements but is an important part of operating the multimeter 4 5 1 Beeper Control Normally the multimeter will emit a tone whenever certain conditions are met For example the multimeter will beep when a stable reading is captured in reading hold You may want to disable the beeper for certain applications When you disable the beeper the multimeter will not emit a tone when 1 Alimit is exceeded in a limit test 2 Astable reading is captured in reading hold Disabling the beeper has no effect on the tone generated when 1 Aninternal error is generated 2 The continuity threshold is exceeded 3 Afront panel key is pressed The beeper state is stored in non volatile memory and does not change when power has been off or after a reset The beeper is enabled when the multimeter is shipped from the factory Use the following steps to change the beeper s state 1 Press wi to enter the menu on the menu level A MATH MEU will be displayed 2 Usel 4 or 5 key to move across to the SYS MEU on the menu level C SYS MEU will be displayed Press V to move down to the command level within the SYS MEU Use 4 or gt key to move across to the BEEP command 1 BEEP STR will be displayed Press W to move down a level to set the beeper control Use 4 or gt
64. owing subsystem commands DISPlay FUNCtion 9 VOLTage CURRent RESIstance 9 FREQuency PERiod HOLD TRIGer FETCh Model TH1942 supports following common commands RST TRG IDN 6 3 1 DISPlay subsystem The DISPlay subsystem commands are mainly used to control the display of the TH1942 and are summarized in Table 6 2 Table 6 1 DISPlay Subsystem Commands Summary Command Function Description DISPlay ENABlIe lt b gt Enable or disable front panel dispaly ENABle Query state of the display ENABle lt b gt Command syntax DISPlay ENABle lt b gt Command Parameter lt b gt OorOFF Disable front panel display 1 or ON Enable front panel display Query ENABle Query state of the display Description This command is used to enable or disable front panel display circuitry When disabled the instrument operates at a higher speed While disabled the display is frozen All front panel controls except LOCAL are disabled Normal display operation can be resumed by using ENABle command or pressing LOCAL key to enable the display 6 3 2 FUNCtion subsystem The commands in this subsystem are used to configure the measurement function subsystems and are summarized in Table 6 2 Table 6 2 FUNCtion Subsystem Commands Summary fp XI Be fey a8 FUNCtion lt name gt Select measurement function VOLTage AC VOLTage DC RESistance FRESistance CURRent
65. p r return r x ax ax 7 show serial operation ax 8 show serial receive ready initialize the serial port void port init int port unsigned char code union REGS r r X dx port serial port r h ah 0 int14 functionO initial serial port r h al code initialization code int86 0x14 amp r amp r
66. pton These commands are used to establish a reference value for the specified function When reference is enabled REFerence STATe the result will be the algebraic difference between the input signal and the reference value Reading Input signal Reference From the front panel reference is called relative REL The REFerence n command is coupled to the ACQuire command The last command sent REFerence n or ACQuire eatablishes the reference When a reference is set using the REFerence n command the REFerence Query command returns the programmed value Conversely when a reference is set using the ACQuiry command the REFerence Query command returns the acquired reference value STATe lt b gt Command syntax CURRent AC REFerence STATe lt b gt Control reference for ACI CURRent DC REFerence STATe lt b gt Control reference for DCI Command parameter lt b gt 1orON Enable reference 0 or OFF Disable reference Query STATe Query state of reference Description These commands are used to enable or disable Reference for the specified function When enabled the displayed reading will include the programmed reference value When disabled the displayed reading will not include the reference value ACQuire Command syntax CURRent AC REFerence AC Quire Acquire reference for ACI CURRent DC REFerence ACQuire Acquire reference for DCI Description When one of these commands is sent the measur
67. r before receiving a query response For some commands that will take a long time to execute for example reset command the controller should keep waiting to avoid the next command being lost when TH1942 is executing the former command Please refer to Chapter 8 for serial interface program examples 5 3 Data Format TH1942 outputs the measurement results using the ASCII character string format via the GPIB bus The data format is described in the following Figure 5 3 SD DDDDDDESDDD lt NL gt S D number 0 to 9 E exponent sign is omitted NL New Line ASCII code is 10 Figure 5 3 Data Format Chapter 6 SCPI Command Reference This chapter provides descriptions of all TH1942 s available GPIB commands which correspond to Standard Commands for Programmable Instruments SCPI command sets Use this chapter as a reference 6 1 Command structure TH1942 commands are divided into two types GPIB common commands and SCPI commands The GPIB common commands are defined in IEEE std 488 2 1987 and these commands are common for all devices Not all GPIB commands are supported by the TH1942 The SCPI commands are used to control all of the TH1942 s functions The SCPI commands are tree structured three levels deep The highest level commands are called the subsystem commands in this manual So the lower level commands are legal only when the subsystem commands have been selected A colon is used to separate the high
68. reference is set using the REFerence n command the REFerence Query command returns the programmed value Conversely when a reference is set using the ACQuiry command the REFerence Query command returns the acquired reference value STATe b Command syntax RESistance REFerence STATe lt b gt Control reference for O Command parameter lt b gt 10rON Enable reference 0 or OFF Disable reference Query STATe Query state of reference Description These commands are used to enable or disable Reference for the specified function When enabled the displayed reading will include the programmed reference value When disabled the displayed reading will not include the reference value ACQuire Command syntax RESistance REFerence ACQuire Acquire reference for O Description When one of these commands is sent the measurement input signal is acquired and established as the reference value This command is typically used to zero the display For example if the instrument is displaying a 0 10 offset sending this command and enabling Reference zeroes the display This command is functional only if the instrument is on the specified measurement function Sending this command while in any other function causes an error Also if the latest reading is overflowed or a reading has not been triggered an error occurs when this command is sent 6 3 6 FREQuency and PERiod subsystem The commands in this subsystem are used
69. rom the date of shipment During the warranty period we will at our option either repair or replace any product that proves to be defective 1 7 Limitation of Warranty This warranty does not apply to defects resulting from product modification without our express written consent or misuse of any product or part This warranty also does not apply to fuses software or problems arising from normal wear or failure to follow instructions THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES NEITHER TONGHUI ELECTRONICS NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF TONGHUI ELECTRONICS HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES SUCH EXCLUDED DAMAGES SHALL INCLUDE BUT ARE NOT LIMITED TO COSTS OF REMOVAL AND INSTALLATION LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON OR DAMAGE TO PROPERTY Chapter 2 TH1942 Overview 2 1 Front Panel Summary The front panel of the TH1942 is shown in Figure 2 1 This figure includes some important abbreviated information that should be reviewed before operating the instrument 2 Math function keys 1 Function keys Input terminals
70. ror Also if the latest reading is overflowed or a reading has not been triggered an error occurs when this command is sent 6 3 4 CURRent subsystem The commands in this subsystem are used to configure and control current measurement function and are summarized in Table 6 4 Table 6 4 CURRent Subsystem Commands Summary Command Function Description Default CURRent DC Path to configure DC current NPL Cycles lt n gt Set integration rate line cycles 0 5 to 2 1 NPL Cycles Query line cycle integration rate RANGe Path to configure measurement range UPPer n Select range 0 to 20 20 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence lt n gt Specify reference 20 to 20 0 STATe b Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value CURRent AC Path to configure AC voltage NPL Cycles lt n gt Set integration rate line cycles 0 5 to 2 1 NPL Cycles Query line cycle integration rate RANGe Path to set measurement range UPPer n Select range 0 to 20 20 UPPer Query range AUTO lt b gt Enable or disable auto range ON AUTO Query auto range REFerence lt n gt specify reference 0 to 20 0 STATe b Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value
71. ry defaults reset the instrument to the factory settings when following step by step procedures Table 2 2 lists the factory default settings Table 2 2 Factory Default Settings Setting Factory Default Function DCV Range AUTO Rate Medium Remote Local Local Trigger Mode Immediate Relative Mode OFF Compare Mode OFF HI Limit 1 Lo Limit 1 Percent Mode OFF Reference 1 Max Min Mode OFF Reading Hold OFF Secondary Display Mode OFF Cal Mode OFF 2 6 6 Warm up time Model TH1942 is ready for use as soon as the power up sequence has completed However to achieve rated accuracy and stability allow the instrument to warm up for half an hour If the instrument has been subjected to extreme temperatures allow additional time for internal temperatures to stabilize 2 7 Display The display of Model TH1942 is primarily used to display readings along with the units and type of measurement Annunciators located on the left right and bottom indicate various states of operation See section 2 2 for a complete listing of annunciators Chapter 3 Basic Measurements 3 1 Preparation One of the first things you would like to do with your multimeter is to become acquainted with its front panel We have provided some exercises in foregoing chapters about preparations for use and operations of front panel The front panel has six rows of keys to select various functions and operations Most keys have a shifted function printed in
72. s tirer tta ete reni rt eter bled ere nep be Fond ube lE 16 25 5 POWSI DIT DEBITAS sisse Riu rot EUR oda FEER enun tu TE oux L7 26 6 Wal U TIM T 17 2 T TIUS Pay i cas ae Gave RR ud oxen tana RR Gait odes la KR REESE UK chal RVE NER A SR KR URE EUR KR ERES NER NE EUN REN KEEN KR Ne EE RERUMS 17 Chapter 3 Basic Measurements p m M 18 3 1 Preparation ES 18 3 2 Measuring Voltage ehe nente ho Ee ee PASE E NS EET ER HIE SCENDE NAE REPRE ES te 18 oEuN Re enne cM Pump mr 18 3 3 Measuring Current EEUU 19 Rcs TSU NS Tc 19 3 3 2 Front Panel Fuse Replacement esssseeeseseeseessee eee te ene tetn ete tn ttt tn tns tet nitentes 21 3 4 Measuring Resistance M E 22 34A COME m M 22 34 2 Shielding eR 22 3 3 Measuring Frequency and Period it errore t teh b e c E ep EE eng o aa Et 23 3 5 1 Trigger Level and Measurement Errors essere 23 3 5 2 Gate TIMO e 23 3 9 9 INST Mc ninesi eieae EE EERE EE EEEE AEE EEE A ERS 23 SO Measurins Con nUity esiin ei E e eere ipie s ete ete ed Td sere LCS UD OLI 24 OP CORTecDOrIS eset cep aside deat alus ence pd wat abd tend mn thet 24 3 7 Testing Diode i cascssvctadvuces sesceseoadeasiueclssatensdoreds eeteeena stem busdinatmulocsbestiers cwdiovemidacdneliobamtarneeliaee teins 25 CN E eoa ure acs inc
73. serial interfaces define PORT 0 include dos h include stdio h include stdlib h include ctype h include string h include conio h void port_init int port unsigned char code int check_stat int port read serial port state 1 6bit void send port int port char c send a character to serial port char read port int port receive a character form serial port void string wr char ps write a string to serial port void string rd char ps read a string from serial port char input 256 query receive buffer main port init PORT 0xe3 initialize serial port baud 9600 no verify 1 bit stop 8 bit data string wr trig sour bus trg string rd input printf n s input string wr volt dc rang 1 0 string wr func volt ac write string to serial port void string wr char ps char c int m n while check stat PORT amp 256 read port PORT read data until null for ps c 0 for m 100 m m send port PORT ps for n 1000 n n delay 2 wait about 2ms can use dos h libray funtion delay if kbhit amp amp getch 27 if escape key keypress printf nE20 Serial Port Write Canceled exit 1 if check stat PORT amp 256 c read_port PORT break if n break if c ps ps else printf nE10 Serial Port Write Echo Error
74. ss The reading hold feature allows you to capture and hold a stable reading on the display Take steps below to enable and set reading hold function 1 Press sit te to enable reading hold function 2 Press 9i _ to enter the menu on the menu level A MATH MEU will be displayed 3 Use lt gt or key to move across to the TRIG MEU on the menu level B TRIG MEU will be displayed 4 Press W to move down to the command level within the TRIG MEU 1 TRIG MOD will be displayed Use 4 or B to select 2 HOLD WIN Press W to move down to the command level within the HOLD WIN Use 4 or gt key to select a window percentage 0 01 0 1 1 10 Press ENTER to confirm the selection The message SAVED will be displayed to show that the change is now in effect TH1942 automatically exits the parameter level and moves up a level to the command level 9 Use B to move across to the TRIG MOD command on the command level 3 HOLD CNT will be displayed 10 Press W to move down a level to enter a count value Default count is 5 11 Usel lt gt and gt keys to choose a numerical place and use A and V keys to increment or decrement the digits Enter a value of count from 2 to 100 12 Press ENTER to confirm the count The message SAVED will be displayed to show that the change is now in effect TH1942 will exit the parameter level and move up a level to the command leve
75. the dBm calculation If you want to change the impedance reference value after the dBm function is enabled you can take actions as below 1 2 Press sit Es to enter the menu on the menu level A MATH MEU will be displayed Press W to move down to the command level within the MATH MEU 5 dBm REF will be displayed Press W to enter the parameter level and the present impedance reference value will be displayed REF 0000 Use 4 an gt keys to choose a numerical place and use A aday keys to increment or decrement the digits Enter a value from 10 to 99990 Press ENTER to confirm the reference value the message SAVED will be displayed for a moment and TH1942 will return to the command level Press to cancel the reference value input TH1942 returns back to the command level without changing the reference value Press shit key to exit the menu and return to the dB math operation status NOTES The reference impedance and input impedance mentioned in this chapter are totally different Input impedance is inherent in the instrument and could not be changed via foregoing methods dBm is valid for both positive and negative DC voltage The percent math operations are applied after the dBm or dB math Chapter 4 Measurement Options This chapter provides description of the front panel features of TH1942 For those measurement options accessible only by a remote interface refer to Chapter 5 and 6 T
76. to configure and control frequency as well as period measurement function and are summarized in Table 6 6 Table 6 6 FREQency and PERiod Subsystem Commands Summary Command Function Description Default FREQuency Path to configure frequency THReshold Path to select the threshold voltage range VOLTage RANGe n Select threshold range 0 to 750 20 RANGe Query threshold range REFerence lt n gt Specify reference 0 to 1 0e6 0 STATe b Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value PERiod Path to configure period THReshold Path to select the threshold voltage range VOLTage RANGe lt n gt Select threshold range 0 to 750 20 RANGe Query threshold range REFerence lt n gt Specify reference 0 to 1 0 STATe b Enable or disable reference OFF STATe Query state of reference ACQuire Use input signal as reference REFerence Query reference value RANGe n Command syntax FREQuency THReshold VOLTage RANGe n Set voltage threshold range PERiod THReshold VOLTage RANGe lt n gt gt a lt Set voltage threshold range Command parameter lt n gt 0to1010 Specify signal levels in volts voltage threshold Query RANGe Query maximum signal level Description These commands are used to specify the expected input level The instrument will then automatically select the most s
77. to the command level without changing the reference value 6 Press sin key to exit the menu and return to the dB math operation status Notes The dB calculation takes the absolute value of the ratio ViyVggr The largest negative value of dB is 160dB This will accommodate a ratio of Vn 1uV Vgge 1000V 3 9 3 dBm Calculation dBm is defined as decibels above or below a 1mW reference With user programmable reference impedance Model TH1942 reads OdBm when the voltage needed to dissipate 1mW through the reference impedance is applied The relationship between dBm reference impedance and the voltage is defined by the following equation 2 dBm 10log Viv Zeer Zep lmWw Where V is the DC or AC input signal Z reris the specified reference impedance If a relative value is in effect when dBm is selected the value is converted to dBm then REL is applied to dBm If REL is applied after dBm has been selected dBm has REL applied to it To set the reference impedance perform the following steps 1 Press Sn for dBm math operation and the present reference value is displayed REF 0000 Use 4 and gt keys to choose a numerical place and use A ana Y keys to increment or decrement the digits Enter a value from 10 to 99990 Press ENTER to confirm the reference impedance the message SAVED will be displayed for a moment TH1942 returns back to the measurement status TH1942 will display the result of
78. tracting the offset from the actual input zeroes the display as follows Displayed reading Actual Input Reference Select a range that cannot accommodate the relative value does not cause an overflow condition but it also does not increase the maximum allowable input for that range For example on the 5V range Model TH1942 still overflows for a 5 1V input To set a REL value press Re when the display shows the value you want as the relative value The REL annunciator turns on Press Re a second time to disable REL 4 1 3 Rate The RATE operation sets the integration time of the A D converter the period of time the input signal is measured The integration time affects the usable digits the amount of reading noise as well as the ultimate reading rate of the instrument In general the fastest integration time FAST set from the front panel or remote interface results in increased reading noise and fewer usable digits while the slowest integration time provides the best common mode and normal mode rejection In between settings are a compromise between speed and noise The RATE parameters are explained as follows Fast FAST sets speed to 25 readings per second Use FAST if speed is of primary importance however it is at the expense of increased reading noise and fewer usable digits Medium Medium sets speed to 10 readings per second Use Medium when a compromise between noise EE performance and speed is acceptable
79. ty Test Measuring range Beeper on 500 000 100 5 0000KQ 1000 50 000KQ lt 1kQ 500 00KQ lt 10kQ 5 0000MQ 100kQ 50 000MQ lt 1MQ 3 6 1 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is as follows 1 2 3 4 Connect test leads to VQ and COM terminals Select Continuity measurement function by pressing Shift Co Connect test leads to the resistance under test as shown in Figure 3 5 Take a reading from the display DC AC TH1942 50000 count Multimeter DC V A6 V FAST 4 EE Period 7 a HEB OHM a a AC DC EN Comp Rel flax Nin 2nd Hold Rate Trig oN OFF Menu Local ZUR CSJC CJ GI G e com uum PONER So RESISTANCE To Note Source current flows from the VQ to COM terminals Figure 3 5 Continuity Measurement 3 7 Testing Diode Model TH1942 can also be used to measure the forward voltage drop of general purpose diodes and the zener voltage of zener diodes A current of 0 5mA will be selected for diode measurement Note Diode test has a non selectable reading rate of Medium 3 7 1 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is as follows 1 Connect test leads to VQ and COM terminals
80. u must send the command with ON or 1 parameter as below HOLD STATe ON or HOLD STATe 1 Parameter types The following are some of the more common parameter types b Boolean Used to enable or disable an instrument operation 0 or OFF disables the operation and 1 or ON enables the operation Example CURRent AC RANGe AUTO ON Enable auto ranging name Name parameter Select a parameter name from a listed group Example name MOVing REPeat RESistance AVERage TCONtrol MOVing lt NRf gt Numeric Representation format This parameter is a number that can be expressed as an integer e g 6 a real number e g 25 3 or an exponent e g 5 6E2 Example MMFactor 5 lt n gt Numeric value A numeric value parameter can consist of a NRf number or one of the following name parameters DEFault MlNimum MAXimum When DEFault parameter is used the instrument is programmed to the RST default value When the MINimum parameter is used the instrument is programmed to the lowest allowable value When the MAXimum parameter is used the instrument is programmed to the largest allowable value Examples CURRent DC NPLCycles 1 CURRent DC NPLCycles DEFault CURRent DC NPLCycles MINimum CURRent DC NPLCycles MAXimum 6 2 2 Short form Rules Use the following rules to determine the short form version of any SCPI command e If the length of the command word is four letters or less no short form version exists E
81. xample AUTO AUTO These rules apply to command words that exceed four letters lf the fourth letter of the command word is a vowel delete it and all the letters after it Example immediate imm Rule exception The short form version of the following command uses only the first two letters of the word TCouple tc f the fourth letter of the command word is a consonant retain it but drop all the letters after it Example format form f the command contains a question mark query or a non optional number included in the command word you must include it in the short form version Example delay del Command words or characters that are enclosed in brackets are optional and need not be included in the program message 6 2 3 Basic Rules of Command Structure Letter case upper and low is ignored For example FUNC VOLT DC func volt dc Func Volt Dc Spaces is used to indicate a space must not be placed before and or after the colon For example wrong FUNC VOLT DC right FUNC VOLT DC The command can be completely spelled out or in abbreviated type In the following description short form will be printed in upper case For example FUNCTION VOLTAGE DC FUNC VOLT DC The command header should be followed by a question mark to generate a query for that command For example FUNC 6 2 4 Multiple Command Rules The semicolon can be used as
82. y DC I Feagee TH1942 50000 count Multimeter oe v AUTO n 3nni cmi HL EN ggttiedmVAC X Rs 2nd Rate li ji Menu Local 2L Je CO C E GI O o omm ex V V Ne y DC VOLTAGE SOURCE POWER L 7 Input Resistance 10MQ CAUTION Maximum Input 1010V peak RJ z 7s 85 jo lt 2 EN a 5 3 V o 8 r o g a C f N His d f DC AC T 6 Vangie TH1942 50000 Count Multimeter v ac v MED AUTO E rer i C Freq O0 Hm HL dB dBm ma pe T T 6 Ot em V I C Comp O Rel We lax Min We mA a 2nd Hold P Caste Trig B m p Local LT E bi a lt gt Y A Aite es e shift p AL eur gt a y y POWER i d AC VOLTAGE SOURCE S J CE Input Impedance 1 1MQ and 100pF CAUTION Maximum Input 750V RMS or 1000V peak 3 X10 V Hz Figure 3 1 DC and AC Voltage Measurement Connections 3 3 Measuring Current Model TH1942 current measurement range 5mA 50 mA 500 mA DC only 5A 20A Maximum resolution 100nA on 5 mA range 3 3 1 Connections Assuming Model TH1942 is under factory default conditions the basic procedure is

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