All spectrophotometers require periodic calibration to ensure accurate measurements. The DTP41 is designed to ask for calibration every 24 hours of power up time, but many programs require calibration at the start of the program. To force an instrument calibration manually proceed as follows:

Reflection Calibration:

• Begin by locating the Color Reflection Reference (PN DTP41-100). It is located in a protective envelope. This is a calibrated and certified media NOTE: Each reference for a DTP41 has a serial number, and is to be used only with the instrument it came with!
  
  
• Apply power to the Spectrophotometer.
  
  
• Insert the calibration strip, so that the black and colored squares, line up with the mark on the face of the instrument. Insert it until it hits the back rollers, this is approximately three inches.
  
  
• Push and hold the black button, until the light turns solid amber.
  
  
• Press the black button again, the amber light will begin flashing. You will hear the motor start, but the strip will not go anywhere-THIS IS NORMAL.
  
  
• The light will flash green and then begin to flash amber again. In approximately one second the calibration reference should be pulled through.
  
  
• If the calibration was performed successfully, the light will return to green. If the calibration failed, the light will begin flashing amber rapidly.   If the calibration fails, wait for the error to time out: try to calibrate again.
  
  
• After a successful calibration - return the Color Reflection Reference strip to its protective envelope.

A transmission calibration is recommended for the DTP41/T approximately once per week. This calibration must be initiated via computer command.   Most third-party software solutions will ultimately have this option embedded within their structure.   In the event you encounter a package that lacks this routine you may use the following as a workaround: 

Transmission (Black) Calibration:

• Locate and launch X-Rite's ToolCrib utility program.
• Select the appropriate instrument and COM port.
• Next select the terminal tool.
• To prove a working interface, type the letters "SV" followed by a carriage return (the Enter key).   The Software should now come back with DTP41 for the instrument you are connected to and the firmware version.
• Place the designated end of the Color Reflection Reference Envelope under the alignment mark.
  Slowly insert past the front idle rollers until it rests firmly against the rear drive rollers.
• Type the command "00CT" followed by a carriage return.
  The instrument will beep and the LED status indicator should begin to blink amber. The DTP41/T will take five measurements. Following the last measurement, the unit will beep again and the indicator will turn green. NOTE: This is a static measurement, the envelope is not pulled through the instrument.
• Remove the Color Reflection Reference Envelope from the instrument