RIGOL DP800 Programmable Linear DC Power Supply User Guide

DM3058 Digital Multimeter
Instruction Manual

Data logger device for DM3058 digital multimeter

The suggested workflow for using the data logger is to set up measurement type and range using multimeter controls. Then choose the measurements logging rate on the data logger and start recording. Each recording session is saved as a file that can be retrieved by connecting the data logger to the PC as a USB flash disk.
This manual consists of the following sections:

1. Data logger controls.
2. Measurements logging mode.
3. Connecting the data logger and starting measurements recording.
4. Using USB disk mode and managing measurement files.
5. Additional notes on some measurement types.

Data logger controls

LCD screen and four control buttons are located on the front side of the data logger.

1. The START / STOP button is used to start and stop recording and also to CONFIRM some actions.

2. UP and DOWN buttons are used to change measurements log intervals and scroll through files.

3. The MODE / SELECT button is used to change logging mode and also to choose additional settings.

4. Status led lights up while the measurement is requested and also to indicate other activity.
   Other inputs and controls are on the left side and back of the data logger.

5. The power On button is used to turn on the data logger. There is no power-off option. The data logger will stay on until the multimeter is turned off.

6. The micro USB port is used to connect the device to the PC as a USB flash disk to retrieve saved measurements. The data logger will turn on while connected to the USB.

7. A recessed firmware update button can be used while connecting the device to a PC as a USB device to perform firmware updates.

8. RJ45 port connects to the serial port of the DM3058 multimeter. Use the cable provided with the data logger. Additional USB-A type connection provides power to the data logger while it is connected to the multimeter. The USB port in front of the DM3058 multimeter can be used for this purpose.
   Another USB power adapter can be used if it provides a reasonably stable 5V supply. In this case, the data logger will stay on while an external 5V supply is available even if the multimeter is turned off.

Measurements logging mode

Based on how the DM3058 measurements loop works there are two measurement logging modes used by the data logger ­ interval mode and continuous mode. In interval mode measurements logging period can be set from 1 second to 120 seconds. Data logger triggers and records measurements at this selected rate. Continuous mode adjusts to the internal measurements clock of the multimeter. It is suited for logging fast continuous measurements at a uniform rate. It is not, however, possible to choose any arbitrary recording period in continuous mode as the DM3058 measurements cycle depends on the selected rate (fast, medium, slow) and measurements type. A multimeter is triggered to take measurements continuously and by logging every reading or skipping some readings uniform measurements logging rate is achieved. Another benefit for continuous mode measurements is that all changing values can be observed on a multimeter while just some are logged to file. Measurements at the FAST rate can be recorded at 24 ms period (or multiples of 24 ms); measurements at the MEDIUM rate can be recorded at about 50 ms period (or multiples of that); measurements at the SLOW rate can be recorded at about 400 ms period (or multiples of that). There are some exceptions based on measurement type. The data logger detects the actual measurement rate and saves that information with every file.

Connecting the data logger and starting measurements recording

Before using the data logger it is necessary to change the serial baud rate setting on the DM3058 multimeter. This is done by pressing the button on the multimeter and selecting “I/O” ­ “RS232” ­ “Baud” and choosing a value of 57600. The “Parity” setting should be left at the default state “None”. The Baud rate setting will remain until changed or the settings of the multimeter are reset to defaults. Press again to exit this screen.
Connect the cable provided with a data logger to the serial port at the back of the multimeter and an additional USB connection to the USB port at the front of the multimeter. Don’t forget to fix the serial port connection using screws as it might get loose easily. Connect the RJ45 connector to the data logger. Turn on the multimeter if it is not powered already and turn on the data logger by pressing the Power On button. If a 5V supply is available LCD screen turns on and the data logger queries the multimeter using a serial connection. The multimeter should change to remote control mode indicated by “Rmt” on the top right corner of the multimeter display. If the DM3058 or DM3058E multimeter model is detected data logger shows a startup screen with measurements logging interval set to 1 second.

If the multimeter was not detected by querying serial commands data logger displays a single CONNECT prompt. This is most likely caused by the wrong RS232 baud rate setting on the multimeter. The connection can be re-checked by pressing the START/STOP button.
To change measurement settings using multimeter controls it is necessary to exit remote control mode. This is done by pressing  the button on the multimeter. Local control mode is indicated by “Lcl” on the multimeter display. Set up desired measurement type using multimeter controls.
To start measurements logging in interval mode desired logging period can be set using the UP and DOWN buttons on the data logger. Holding the UP and the DOWN button will continue to change the set value. Pressing the MODE button next to the displayed interval value switches to continuous measurements logging mode and the data logger queries the multimeter for measurement rate. Measurements period value next to the MODE button changes to some value in ms or seconds with decimal digits according to detected measurements type. Desired measurements logging period can be changed using the UP and DOWN buttons. Pressing the MODE button once again switches back to interval mode where measurements logging period can be set in whole seconds.

Measurements logging is started by pressing the START/STOP button. While measurements are logged light on and  buttons should turn off as the multimeter is set to external triggering mode. The following information is displayed on the data logger screen:
Measurement type (like VOLTAGE DC, CURRENT DC, 2 WIRE RES, 4 WIRE RES, DIODE, etc.); Received measurement value in scientific format (two values in dual measurements mode); Current file number; Measurements counter.

Pressing the MODE button while measurements logging is active changes the display to the measurements interval information screen.
In interval logging mode this will show a seconds counter until the next measurement will be triggered. The second counter is not displayed if the measurement interval is set to one second. Although interval mode measurements are triggered at the exact time when the counter elapses measurements will be processed according to the internal clock cycle of the DM3058 multimeter.
In continuous logging mode measurements interval display will show the actual interval between logged measurements in ms or seconds with decimal digits. Interval between logged measurements depends on the internal measurements clock of the multimeter and the selected measurements rate. The rate set with data logger controls acts as a multiplier for the measurement cycle of the DM3058 multimeter. The actual measurements interval will not be exactly the same as selected while setting the desired interval in continuous mode. Measurements interval is detected and included in the data file.
Press the MODE button again to show the last received measurement instead of measurement interval information.
Blue status led lights while the measurement is requested from the multimeter. Measurements triggering is indicated also by green/yellow led on the back side of the data logger. In the interval, mode multimeter performs a single measurement when second counter is elapsed. Two measurements are done in dual measurements mode. In continuous logging mode data, the logger triggers measurements continuously but the measurement value is requested and logged according to the selected logging interval.

Pressing UP or DOWN button while measurements logging is active changes display backlight dimming.
Measurements logging is stopped by pressing the START / STOP button. The measurement file is closed and the file is counter-advanced. A multimeter is set to Single triggering mode. To use any control on the multimeter it is necessary to exit the remote control mode indicated by “Rmt” on the multimeter display. It is done by pressing the button on the multimeter. Free running measurements can then be resumed by pressing a button or any other settings can be changed using multimeter controls.

Using USB disk mode and managing measurement files

Measurement files are retrieved by connecting the data logger to the computer using the micro USB port. In USB mode data logger mounts as a standard USB flash disk. No additional driver files are necessary. The data logger can be disconnected from the multimeter using the RJ45 connector. It is not necessary to turn off the multimeter before unplugging the RJ45 connector but measurements logging should not be active when disconnecting. It is also possible to leave the data logger connected both to the computer USB and multimeter or connect and disconnect the USB connection as needed.
At first USB connection flash disk mode of the data, logger takes priority. USB disk can then be is dismounted by unplugging the micro USB connection or data logger controls can be used to switch between USB disk and data logging mode quickly.
Pressing and holding the MODE button while the data logger is in data logging mode but measurements logging is not active opens the saved measurement files list. If a USB connection is detected ENABLE USB prompt will show with CONFIRM and SKIP options. Pressing CONFIRM activates USB disk mode and SKIP proceeds to the files list screen. If the USB connection is not detected files list will open without additional prompts.

Use the UP or DOWN button to scroll through the files list. Pressing and holding the UP or DOWN button advances to the next few files and if the files list exceeds one screen first or the last file is selected. This can be used to quickly move to the end or beginning of the file list.
Pressing the MODE button at the files list screen cycles through file information such as measurements type, measurements count and selected file DELETE prompt. While the file DELETE prompt is active pressing the START / STOP button changes the DELETE prompt to CONFIRM. Pressing the START / STOP button once again deletes the selected file. The remaining files will be renumbered sequentially and the file count updated. (It is also possible to delete files in USB disk mode without using data logger controls.) Changing the selected file with the UP or DOWN button clears the DELETE or CONFIRM prompt and advances to the next or previous file. Pressing and holding the MODE button exits the files list and returns to the initial screen with the interval logging mode set.
Flash memory pages used by measurements are indicated by ruler type progress bar along the bottom side of the data logger screen. There are 4096 pages of 130 measurement records available that can be used by 30 files. When the file count limit is reached current file number will change to FILE MAX and further measurements logging will not be possible until the file is deleted although free memory pages might be available. If all internal flash memory pages are used MEMORY FULL message is displayed until any file is deleted.

Measurement files in USB disk are formatted as CSV text files. The first line of each file shows the measurement type and detected interval between measurements in continuous mode or seconds between measurements in interval mode. The remaining lines contain measurement values in scientific format. Dual mode measurements show two measurement types in the first line and two measurement values separated by semicolons in the remaining lines. Measurement interval in dual measurement mode is a time of one complete measurement cycle that consists of two measurements.
File formatting allows files to be opened in Microsoft Excel directly without a data importing sequence. OpenOffice Calc can be used to open CSV files as well. Semicolon should be selected as a field separator and the “Detect special numbers” option selected in the OpenOffice Calc Text import wizard. Any other software that can parse scientific number format can be used as well. Dot symbol “.” should be used as a decimal separator in corresponding regional settings of operating systems or data processing software.

Unnecessary files can be deleted from the USB disk while the data logger is connected to the computer. It deletes corresponding measurement records from internal data logger memory. Once the file is deleted there is no way to revert it. Next time measurements logging mode is activated or the USB disk is connected files will be renumbered sequentially so that there will be no missing file numbers in place of deleted files. Although it seems possible to copy files to a mounted USB flash disk nothing is actually written to flash memory by doing so.
While the data logger is connected to the computer as a USB flash disk it can be disconnected from the USB by pressing and holding MODE (bottom right) button. This opens the DISCONNECT USB prompt with CONFIRM and BACK options. Pressing the UP or DOWN buttons changes prompt to FW UPDATE. Pressing CONFIRM activates the selected choice, pressing BACK returns to USB disk mode without changes.

If DISCONNECT USB is activated USB disk dismounts and the data logger queries the multimeter using a serial connection. Display changes to the initial measurements logging screen and the multimeter should go to remote control “Rmt” mode. If there is no response from the multimeter CONNECT prompt is displayed. If the FW UPDATE prompt is activated USB disk is disconnected, the display dims with status led on and the data logger enters firmware update mode enumerating as a USB HID device. Firmware can be updated using the additional utility. Even if FW UPDATE mode has been activated no changes to firmware are made unless the update utility is used. Disconnect and power cycle data logger to clear firmware update mode.
The internal measurements record system can be reset by holding the MODE button while the data logger is powered on. This opens ERASE FILES prompt with CONFIRM and SKIP options. Pressing CONFIRM erases all flash memory pages and resets the internal records system to a blank state. Pressing SKIP proceeds with a startup. ERASE FILES option can be used to delete all files quickly and to clear any internal records system error. Holding the MODE button activates ERASE FILES prompt only if the data logger is powered on while connected to a multimeter or if the unpowered data logger is connected to a USB.

Additional notes on some measurement types

A useful feature of the DM3058 multimeter is dual mode measurements ­ ability to measure two types of values. There are some limitations to using it. Probably the most useful mode is to measure both the voltage and current of some circuits. Connections for such measurements should be made in a way that both voltage and current share the same return path. Another restriction is that secondary measurement always runs in auto range mode. Some trial and error is needed to avoid internal relays of the multimeter clicking continuously while changing modes. This will break measurement timing and most likely is not recommended over longer periods. For fast-changing measurement values, it can be significant that both measurements are not processed at exactly the same moment. At first, primary measurement is done and then secondary. The time between primary and secondary measurements depends on the selected measurement rate.
While testing measurement ranges and fine-tuning dual mode measurements it may happen that the multimeter skips some internal measurement cycle and starts to display primary measurement value in place of secondary and vice versa. Correct values are usually transmitted to the data logger over a serial connection. To clear this situation it is necessary to turn the multimeter off and on again.
To avoid switching relays when the measured value changes significantly it might help to use a fixed range setting adjusting it to the largest expected value. Although it is possible to mix AC and DC measurements in dual measurements mode changing from AC to DC mode will always switch internal relays.
The measurement period of capacitance varies greatly depending of the capacitance value. Measurement of frequency is done at about 0.8 seconds intervals. If the frequency is used as a secondary measurement type it is possible to read measurements more often in continuous mode but the actual frequency value is updated at about 0.8 seconds rate.
Sensor measurement mode values are reported over serial connection but not corresponding converted display values. Commands to retrieve converted sensor values are not provided in the DM3058 command set. Although sensor measurements mode is detected and supported by data logger only measured value is logged without knowing what type of measurement it is and how it was converted to display value.

This manual is written by KPT for the DM3058 data logger device Licensed under Creative Commons Attribution- NoDerivatives 4.0 International License

References

• 示波器-数字示波器-信号发生器-频谱分析仪-直流电源-普源精电科技-RIGOL TECHNOLOGIES, Co. LTD

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