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Display Temperature Data Logger

This temperature data logger has a high accuracy RTD probe and a large digital display. The display provides current and min/max readings so you get the information you need without having to download the data. The display gives on site, at a glance information that will save you time.

  • RTD Probe with .5F (.3C) accuracy
  • USB enabled fast downloading
  • Flash memory option for easy data transfer
  • Audio and Visual alarms
Calibration Method

Calibration ensures Regulatory and Audit Compliance

Sm420 front 864
Sm420 lft angle 619
Sm420 rt angle 569
Sm420 lft side 444
Sm420 rt side 319
Sm420 back 242
Sm420 probe 161
Sm420 sdcard 54
Sm420 top 23

Download Images: Print Quality | Hi-Res

Important Information

DicksonWare Software is needed to communicate with this product and is sold separately.

Dickson Expert Services

Our Dickson Data Division has specially trained representatives to address the needs of customers with large installations or unique demands. Please call 888-452-4626.

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Description Data Logger with Large Display and High Accuracy Probe USB Display Logger with High Accuracy Temperature and Humidity
Price $539.00 $199.00
Remote Probe Icon compare check Icon compare check
  • Audible
  • Visual
  • Audible
  • Visual
Battery Operation Icon compare check Icon compare check
Temperature Range Icon question
  • -50.0 to 350.0F
    (-45.0 to 176.0C)
Temperature Accuracy
  • +/-0.5F from -50.0 to 350.0F
    (+/-0.28C from -46.0 to 176.0C)
Compare Compare
Add to Cart Add to Cart
  • Alarm Type Audio/Visual on High/Low Temp Limits
  • Ambient Operating RH Conditions 0-95% RH non-condensing (Logger only)
  • Ambient Operating Temperature Conditions -4.0 to 158.0F (-20.0 to 70.0C)
  • Approvals CE
  • Battery Backup Yes, with use of AC Adapter
  • Battery Life (Avg) 6 Months
  • Cable Details USB - Male Series A plug to 5 pin Male Series B mini plug. Serial - 9 pin female D-shell to male 2.5mm stereo plug
  • Cable Length 6.0ft
  • Calibration Options N100, N300, N400, N520
  • Channels CH1: Temperature
  • Data Capacity 32,000
  • Dimensions 1.6 x 3.0 x 4.0in
  • Display Dimensions Height 1.375
  • Display Dimensions Width 2.0
  • Display Resolution 0.1 from 0.0 to 999.99; 1 over 1000
  • Display Type LCD
  • Display Update Rate 10 Seconds (Battery Power), 1 Second (AC Power)
  • Download Time 1 Minute (USB), 3 Minutes (Serial)
  • Download Type USB / Serial / Flash Card
  • IP Rating 20
  • Included Accessories Four AA Batteries, Quick Start Guide and RTD Probe. *Software is not included.
  • Memory Type EEPROM, Removable Flash Storage Device
  • Minimum Software Version Required 9.0
  • Mounting Options Wall Mount (With Keyhole)
  • PC Requirements HelpMicrosoft Windows 98 or better; 16 MB RAM, 1 free USB root hub, CD drive, VGA monitor or better
  • Power Source Four AA Batteries (User Replaceable) *AC Adapter is not included, but can be used.
  • Power Source Notes AC Power is optional, but not included.
  • Power Status Indicator LCD Display
  • Probe Cable .110 inch diameter (cord only); .190 inch (probe tip only)
  • Probe Tip Length 2.0inch
  • Remote Sensor Length 6
  • Remote Sensor Type Platinum RTD Probe
  • Response Time 30 Seconds to 63% of Full Scale
  • Sample Interval User Selectable (from 1 second to 24 hour intervals, in 1 or 10 second increments).
  • Software Options A015, A016, A025, A026
  • Temperature Accuracy +/-0.5F from -50.0 to 350.0F (+/-0.28C from -46.0 to 176.0C)
  • Temperature Range Help-50.0 to 350.0F (-45.0 to 176.0C)
  • Temperature Sensor Type Thermistor/RTD Probe
  • Unit Weight 3 lbs
  • Units/Pkg 1
  • Warranty 12-Month Limited
Why should I calibrate?

All instruments lose accuracy over time due to normal usage and the environmental conditions to which they are exposed.

How often should I calibrate?

For most applications, the recommended calibration interval is every twelve months.

N100 1-Point NIST Traceable Calibration $99.00 Add
N300 3-Point NIST Traceable Calibration $156.00 Add
N400 3-Point Ultima NIST A2LA Accredited Calibration $269.00 Add
What is NIST Calibration?

NIST stands for the National Institute for Standards and Technology. This organization is responsible for maintaining the master for different measurements, such as the standard "foot", standard, "second", or standard "pound". NIST also maintains the standard for temperature, humidity and pressure.

NIST Traceable means that the measuring standard can be traced directly back to the master standard maintained by the NIST organization.

NIST-Traceable does not tell you the measurement accuracy of a metrologty service in any detail. Only metrology services that can document their ISO 17025 standard provided data on their best measurement uncertainty.

AC Adapter Extension Cable 10'

10' Power Extension for R157 AC Adapter

AC Adapter

AC Adapter

Universal Plug Kit for AC Adapter

Set of Three International Power Plugs for AC Adapter

AA Battery

AA Alkaline Battery

Card Reader Kit

Includes USB Reader and Flash Memory Card

Memory Card

Removable Flash Memory Card

AA Batteries

4 Pack AA Lithium Batteries

USB Download Cable

USB Download Cable - length 6 feet (2m)

Serial Download Cable

Serial Download Cable - length 6 feet (2m)

Secure Software

DicksonWare Secure Software with USB Cable


DicksonWare Software with USB Cable

Frequently Asked Questions

  •  Press and hold the Min/Max button for 5 seconds.

Verify that you have the correct version of DicksonWare software installed on your PC. Version 8.0 for all units except the Net Loggers which require Version 9.0

Verify that the correct COM port is selected: From the main Dicksonware screen, click on Logger then Communication, a black dot will appear next to the selected COM port. You may need to select a different COM port. Should you get an error message stating that Device Is Already Open, this could mean that you have the proper COM port selected, but another device, or its software, has it allocated. Palm pilots, for example, will cause this problem, in which case the port is not actually available and you may have to disable that device.

You may need to relocate the download cable to another serial port on the back of the PC and possibly try changing the COM port again in DicksonWare.

If communication has not been established with the previous steps, you may need to remove the batteries and then try all COM port and cable combinations again.

If possible, try another PC

Make sure the USB is unplugged, and that USB is NOT checked in File > Preferences > Serial.

Try removing the batteries and ac power (if applicable) for a few moments, (this will not cause the unit to lose any data within the logger, but you will have to start the unit logging again using DicksonWare).

Batteries may be too low, replace batteries.

Unplug USB cable and plug back in.

If the logger was used in a moist or humid environment condensation may have formed on the unit. Place unit in a warm dry environment for 24 hrs. Clear memory and try again. These loggers are designed for use in a non-condensing environment. If the environment creates condensation, try placing the unit (temperature only models) in a small sealed plastic bag to protect it from condensation.

Make sure that USB is selected under File > Preferences > Serial.

Unplug USB cable and plug back in.

Remove all power to the logger (this will not cause the unit to lose any data within the logger, but you will have to start the unit logging again using DicksonWare) unplug the USB cable, power the logger back on, then reconnect the USB cable.

If the logger was used in a moist or humid environment Condensation may have formed on the unit. Place unit in a warm dry environment for 24 hrs. Clear memory and try again. These loggers are designed for use in a non-condensing environment. If the environment creates condensation, try placing the unit (temperature only models) in a small sealed plastic bag to protect it from condensation.

If possible, try another PC, and/or another USB port.

This is normal when the probe is not connected at the time a sample is taken.

The min/max on the display is not the min/max alarm settings. The min/max on the display shows the temperature or temp/Rh min/max only.

The Flash Memory Download Feature was designed to work with standard MMC cards. MMC Plus cards can cause the unit to stop logging when used to download data. If you think the unit stops logging when the Flash Memory Download Feature is used, you might be using a MMC Plus card. We recommend using Dickson Flash Memory Cards.

Err 1 - No memory card
Err 2 - Memory card locked or protected
Err 3 - Wrong size file (too big) or no data to log yet
Err 5 - Trouble writing file to card
Err 14 - This is a generic fault code. There is something wrong with the card (full or not formated correctly) or there is a hardware issue (a bad connector or no card present - can't see any card). Try another card.
Err 16 - Trouble accessing card
Err 23 - Memory card requires reformatting
Err 7 or 66 - Memory card full
Err 49 - Unknown error

Flash cards not purchased through Dickson should be formatted. If formatted after experiencing issues the unit will have to come back to be reset.

Formatting instructions:
1. Insert flash card into card reader
2. Go to My Computer and right click on the drive letter that corresponds with the card
3. A menu will appear. Choose the format option
4. Another window will appear
5. Under the "File System" heading, drop down the menu and choose the option, if running Windows XP. Choose "FAT" if running Windows 7 or 8.
6. Then click on the start at the bottom of the window

This will format the card in the correct manner for use with the unit.

The RTD probe on the SM420 is very delicate compared to a K-TC probe. Try removing any kinks and straightening the probe out. If the unit does not begin to display the correct temperature, the probe may have been permenantly damaged. Contact customer service to return for repair.

In order to view units over multiple subnets or to view units on non-standard subnet mask, click on the Connect button then select Set Subnet. You can enter a different Subnet here. DicksonWare will not remember this address, and it will need to be re-entered every time you open a new DicksonWare session.

Replace the batteries, they may be low.

When the IP address is set using USB and the logger is then connected to the network, the logger will not be detected until all power (AC and battery) is removed and the unit is then powered on again.

The more files stored on the card, the slower the download. It's a good idea to clear the memory card occasionally.