| 常見問題 |
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數位電錶常見問題 |
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| 數位電錶 |
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| Suppose your condition is in AC 100V and you want to convert the voltage to the 220V. |
| 【Step 1】Verify that the meter is disconnected as shown as the Figure 2-1. |
 Figure 2-1 |
| 【Step 2】Open the voltage setting selector cap as shown as the Figure 2-2. (You might need a pair of tweezers to do so) |
 Figure 2-2 |
【Step 3】Remove the red voltage setting selector from the right middle seam as shown as the
Figure 2-3. (You might need a pair of tweezers to do so) |
 Figure 2-3 |
| 【Step 4】Turn it over to 220V position as shown as the Figure 2-4. |
 Figure 2-4 |
【Step 5】Insert the voltage setting selector back into the socket and close the cap as shown as
the Figure 2-5. |
 Figure 2-5 |
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| 【Step 1】Verify that the meter is disconnected as shown as the Figure 2-6. |
Figure 2-6 |
| 【Step 2】Open the voltage setting selector cap as shown as the Figure 2-7. (You might need a pair of tweezers to do so) |
Figure 2-7 |
| 【Step 3】Remove the red voltage setting selector from the right middle seam as shown in Figure 2-8. (You might need a pair of tweezers to do so) |
Figure 2-8 |
| 【Step 4】Remove the broken fuse from the selector as shown in Figure 2-9. |
 Figure 2-9 |
| 【Step 5】Replace with the new fuse as shown in Figure 2-10. |
 Figure 2-10 |
【Step 6】Insert the voltage setting selector back into the socket and close the cap as shown in
Figure 2-11. |
 Figure 2-11 |
【Step 7】Make sure the power switch on the front panel is in "Power OFF" condition before
plugging as shown in Figure 2-12. |
 Figure 2-12 |
| Power switch: |
 "POWER OFF" |
【Step 8】After finishing the above procedures, you can plug in your power cord as shown in
Figure 2-13. |
 Figure 2-13 |
【Step 9】Press on the power switch on the front panel for activating M3500A as shown in
Figure 2-14. |
 Figure 2-14 |
| Power switch: |
 "POWER ON" |
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Our thermocouple adapter provides standard sockets for both mini connecters and standard connecters. |
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The 2-wire method is commonly used as it is the simplest and most straightforward method. In 2-wire, you can get accurate measurements above 100 kΩ relatively easily. For precision measurements with resistances (ohms) below 100 kΩ, 4-wire works more reliably and conveniently than 2-wire. 4-wire requires 4-wire switching and more cabling. You may decide the tradeoff is acceptable, depending on the accuracy versus complexity requirements of your system.
The following figure shows a 4-wire resistance (ohms) measurement, including lead and switching resistance: |
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| Current (amps) is forced through the source leads (HI, LO). As a result, a voltage develops across the resistance (ohms) under test. By measuring the voltage directly across the resistor using the sense leads, the voltage drop of interconnects (RLEAD) is ignored. |
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The difference is the "delay time setting". For "STEP", the delay time setting is between each channel. For SCAN, the delay time setting is between a 10-channel turn to another. |
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It doesn't matter. However, we suggest that you may fix screws for the better measurement. The metal flakes with the screws connect to the chasses ground; as a result, fix screws could reduce the environmental noise and statics. |
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The USB supports up to 127 different devices. Additional USB devices are connected through hubs in a tiered star topology which consists of multiple USB peripherals connected to a single USB hub and multiple USB hubs connected in a chain, one to another. |
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Yes. We provide a free stand-along program "AP" for customer to transfer the measured data from M3500A to PC even they do not install 「MicrosoftR Office」. |
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Win 98, ME, 2000, XP |
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Yes. You will need Thermocouple adaptor to connect the mini thermocouple connecter. |
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Our M3500A provide 3 wire and 4 wire RTD measurement. |
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| M3500-opt01 Multi-point Scanner Card is not allowed of direct current measurements; however, on-card shunt resistors can be installed for channels 1 and 6 to allow for indirect current measurements. The figures below show the typical configuration for current measurements. |
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| The current through each shunt resistor can be calculated as follows:
I= current being determined
V= voltage measured by multimeter
R= shunt resistance value
Instead of manually calculating current, set up a MX+B math calculation function. (M=1/R and B= 0.). The M3500A will then display the actual current value.
Note: If there are two devices under test, the value of User-installed Shunts(R) have to be the same. |
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M3500A supports 7 types of Thermocouple: E, J, K, N, R, S and T. Via thermocouple adapter, user must measure a known temperature junction (T1) and then modulate the value of reference junction according to the result. The value of reference Junction must be stable, so that user can measure an accurate temperature.
How to modulate the value of reference junction for thermocouple measurement:
1. Configure the thermocouple type and unit. Pressing CONFIG >> SHIFT >> TEMP(TCOUPL), and then using PREV and NEXT to select the type and unit.
2. Measure a known temperature junction (T1). The result of the measurement is Tm.
3. Modulate M3500A reference junction to make Tm=T1.
Reference junction modulation：
Panel:
CONFIG >> SHIFT >> TEMP(TCOUPL) >> NEXT >> NEXT >> SIMULATE >> ENTER
Pressing 「PREV」 or 「 NEXT」 and 「RANGE」 to modulate the reference junction.
PC remote control Command:
「:TCO:RJUN：Sim value」
Example:
If the reference junction=23.0°C, T1=30°C，Tm=25°C, we should modulate the reference junction to 28.0°C to make Tm=30°C. ? |
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USBTMC 是 USB Test & Measurement Class 的簡稱。只要含有 USB 介面的儀器符合 USBTMC，在不受任何平台和環境的限制下，即可透過 VISA 驅動儀器，並與 PC 進行通訊。換言之，透過 VISA 對 USBTMC 儀器的控制，與透過含 GPIB 介面儀器的控制，其程序與操作是一樣的。
USBTMC(USB Test & Measurement Class)：USBTMC是建立在USB之上的一種通訊協定。只要含有 USB 介面的儀器符合 USBTMC，在不受任何平台和環境的限制下，即可透過 VISA 驅動儀器，並與 PC 進行通訊。透過 USBTMC 及 USB488 協定，能像控制 GPIB 一樣來控制 USBTMC 且同時支援觸發 等其他 GPIB 的命令。使用 USBTMC 的好處是不需要增加任何介面，也不需要重新編寫程式， 經搜尋儀器後，只要使用符合 USBTMC 協定的 VISA 層，就可透過 USB 來實現 GPIB 的通訊 方式。只要作業系統上安裝 NI-VISA 3.1 以上版本的驅動程式後，USBTMC 的裝置就能夠被 識別且可以使用。
參考網站 : http://digital.ni.com/public.nsf/allkb/044fa220f32774ed86256db3005850ca .
本公司積極研發 M3500 的 USB 介面已完全符合 USBTMC 的協定，使用者不需要再購買 GPIB 介面卡， 只要利用 USB 介面就可以完全摸擬 GPIB 介面的控制，而達到完全相同的控制功能。而使用者只須到 NI的網站(www.ni.com/visa)下載驅動程式後，再安裝本公司的應用軟體 PT-TOOL、 PT-LINK，就可以 利用 PT-TOOL、PT-LINK 或是自己編寫程式，就能夠控制 M3500A 了。
必須注意的是，不是所有 USB 埠的裝置都支援 USBTMC。製造商必須在裝置韌體上提供 USBTMC 才可以。 不過還是要參考儀器文件來判定是否支援 USBTMC。
請開啟參考程式碼 C 語言範例程式為控制 USBTMC 及 GPIB 的差異處(紅色部分為主要的差異)，可以很清楚的看到， 程式碼幾乎完全一樣 !
參考程式碼 |
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Please set trigger time by pressing the buttons on the front panel.
MENU -> NEXT to TRIG -> ENTER -> NEXT to DELAY -> ENTER. The problem is regarding the time setting
of trigger delay. Then, please in the PT-TOOL software input the remote control command for speeding up
the scan capability. "TRIG:DELAY 0.1". |
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Please do the warm-up step in two hours for solution. Because the temperature of the instrument
and the adapter must be the same so that measuring the value will be stable. To do the warm-up step can
let the instrument and the adapter with the same temperature. |
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Please confirm the version of NI visa is 3.1 or upward. If it is incorrect, please refer to our User
guide in CD we enclosed with the Instrument to link the NI website and download the correct NI Visa
to operate. |
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| 【Step 1】若欲以M3500A Digital Multimeter及Power Supply取代Source meter量測電池的IV曲線,將直接使用電錶的量測電流功能,如圖一所示為一簡單的接線圖,將電錶串聯於待測物及Power Supply的中間,並直接讀取Power Supply的電壓值及電錶的電流值,再轉換成IV曲線,但量測結果往往造成量測誤差,此量測誤差來自於電錶的Burden Voltage 造成,為改善此量測誤差,可使用M3500A的多通道量測卡(SCANNER CARD)將電錶設成量測電壓功能,並可同時藉由Scanner Card量測多點電壓,其接法如圖二所示 |
 Figure 1 |
| 【Step 2】將R_shunt電阻接於待測物及Power Supply之間,則電流將流經R_shunt產生一電壓VR_shunt,以M3500A的Scanner Card的CH1量測待測物電壓,CH2量測VR_shunt電壓,再將VR_shunt/R_shunt得到電流值I,就可劃出正確的IV曲線,並減少Burden Voltage所造成的誤差 |
 Figure 2 |
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