Need Help? Talk to a specialist: 1-630-543-3747


This product has been replaced by the TSB

Our FH121  has been completely redesigned and now goes by Model FH520.

Click on the link to view and order the NEW FH520 Touchscreen Data Logger.


Download Images: |

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.

Frequently Asked Questions

  • Unit may be "locked up", try unplugging transformer and removing the battery. After a few moments, re-power Data Logger with battery only to ensure battery is good, then power up with transformer only to ensure it is good.
  • Is the unit displaying the large characters instead of the graph view? All keys are disabled when displaying the large real time characters.
  • If the graph has reached the end of the screen, when a new pixel is drawn, the unit will blank the screen and redraw the graph shifted to to the left by one pixel. This takes a few seconds to complete and the keys are disabled momentarily.
  • If you are downloading the data, the keys disabled during download and will not function until the down load is complete.
  • Does the unit come on when attempting to communicate with DicksonWare software? If so, the keypad could be unplugged or defective.

The cursor will not function until there is a graph on the screen of at least 2 data points. Also, the cursor will not function if the menus are open or you have the Data Logger set to the large character display mode.

Is the graph at the end of the screen? If so, it may be redrawing the graph, all keys are momentarily disabled for about 3-seconds. This will be more noticeable on smaller horizontal time scales.

This is normal operation if you are downloading, clock will restart when downloading is complete

Unit may need to be reset. Open unit by removing all four screws from the back. Remove back panel and press the reset button for 2-seconds. Older units may not have a reset button, in which case you may reset the unit by shorting leads 4 and 8 (lower left and upper right) from IC location U5 on the PC board.

  • Adjust display contrast by adjusting the trim pot resistor. This can be found on lower right corner of the PC board when you open the unit (loc. R113). Gently turn the resistor with a small Phillips screw driver while watching the display.
  • Is the Data Logger functioning otherwise? Make sure the battery is good and the AC adapter is plugged in.
  • Is the correct version of software being used?
    Minimum requirement is
    DicksonWare or higher
  • Make sure the download cable is not physically defective.
  • Is the correct COM port selected?
  • Try another available COM port through the software.
  • Has the communication speed (baud rate) been changed? It should be set on ADAPTIVE.
  • Check Com port allocations in the PC's Device Manager, make sure the COM port you're trying to use is not "reserved" for something else.
  • Try another logger. (if available)
  • Try another available COM port connection on back of PC.
  • If this is the first time attempting to communicate on this PC, or if new software or programs have been installed since the logger was last used, try installing the software on another PC.
    (not a laptop)
  • Has the unit just been removed from a cool environment? Condensation may have momentarily formed internally, wait for the unit to warm up, it should power up and give all data stored.
  • Is it possible that the Data Logger was programmed to fill up storage space quicker than originally thought?
  • Is the Data Logger set up to WRAP as opposed to STOP when full?
  • Unit may be "locked up", try unplugging the adapter removing the battery, if applicable, then re-power after a few moments.
  • If ONLY the Temperature or Humidity reading is stuck at specific value that sensor is defective or has possibly been damaged.
  • Does the blank space correspond to a time when the Temperature or Humidity rose or fell quickly or fell below or rose above the scale limits on the screen, or was AC power and back-up battery disconnected at the same time? Try a wider vertical range setting or download the data to a PC. If there is still a gap in the data, try resetting the unit. If the problem continues, return for service.

Reading greater or less than the scale limits will not be seen on the display. They may still be seen in the lower left real time value display.

If you are using DicksonWare, look in the setup section to see if one of the channels has been disabled, and if so, re-enable it.

It is possible that one of the sensors is bad, in which case the Data Logger must returned for service.

  • If sensor was saturated, the unit may return to normal after a few hours in a dry environment.
  • What is the environment like where the unit is being used? Is the humidity above 95% or condensing?
  • The Humidity sensor has possibly been damaged and must be returned for service.
  • These units are Dew point CALCULATORS, not meters. The Dew Point reading can be off considerably in humidity environments below 30%.
  • Is there a battery in the unit?
  • Is the battery good?
  • Is the battery in correctly?
  • If battery backup is too low (6 volts or lower) the unit will turn itself off. Readings will also rise before battery is completely dead.
  • If the power outage was only momentary, the unit may not have had enough time to recognize this and switch to battery mode (The unit may lock-up or shut off in this situation)
  • Has the Data Logger just been removed from a cool environment? Condensation may have momentarily formed internally, wait for the unit to warm up, it should power up and give all data stored.
  • Make sure keypad is not unplugged.

What is the tolerance of the unit it is being compared to?

It's ok if the unit is within the sum of the two tolerances

Remember that the unit's tolerance speaks to the Chart Recorder only, there is any additional that applies to the probe

Has an outside calibration house attempted calibration? It may not have been adjusted properly

When was the last time the unit was sent to the Dickson Calibration Lab for a recalibration?

Walk through zero adjustment, found in the manual

For units with Pen Adjustment - rotate screw to adjust the unit to match another unit of greater accuracy after both units have stablized in the same environment.

Chart Recorders - make sure the correct chart is being used.

K-Thermocouple Units
K-Thermocouple capable units are capable of using any K-type thermocouple probe or extension but keep in mind that long extensions to extend the distance may require a Zero adjustment. (Refer to manual)
As a general rule: If the unit is not responding properly, and you have more than one thermocouple, swap probes to see if it is the probe or the unit that is defective.

Voltage Recorders

Make sure the output signal of the transmitter is calibrated to its full measuring range. 

Make sure the range selected on the recorder matches the transmitter exactly and that the proper chart is being used.