3M M2256PW 用户手册

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3M™ Multi-touch Display M2256PW User Guide 

3M Touch Systems, Inc. Proprietary Information – 37531 Rev D

To use the CX command: 

1. Enter the Calibrate (CX) command. The controller sends an initial acknowledgment 

of <SOH>0<CR>. 

2. Touch the sensor at a lower left target, which is located 12.5% (1/8) in from the 

corner of the video image. The controller returns an acknowledgment of 
<SOH>1<CR>. This is a positive response. If you receive a negative response 
<SOH>0<CR>, you can cancel the calibration by issuing a Reset command and then 
start over again. 

3. Touch the sensor at an upper right target, which is located 12.5% (1/8) in from the 

corner of the video image. The controller returns an acknowledgment of 
<SOH>1<CR>. This is a positive response. If you receive a negative response, you 
must start over again.  

Touching the two valid calibration points results in a successful calibration. If either 
calibration point is invalid, the calibration fails. The PX controller restores the previous 
calibration values. If Calibrate fails, repeat the CX process. 

Here are several guidelines for using the Calibrate commands: 

• The controller uses the data immediately before liftoff to register a calibration touch. 

Therefore, you can touch the coordinate target, hold for a few seconds, and then lift 
off. Instructing users to touch this way results in a more accurate calibration. 

• The controller stores the data in non-volatile memory (NOVRAM). Therefore, you 

do not have to calibrate the sensor each time you power on the system. You should, 
however, recalibrate the touch sensor any time the video display changes size or 
resolution. 

• You can cancel calibration at any time during this sequence by issuing a Reset 

command. 

The default calibration targets (points) are located 12.5% (1/8) inward from the corners 
of the video image. For example, the resolution of your Windows-based display is 1680 
x 1050. The Calibrate Extended command calculates the amount to move inward as 
follows: 

•

Amount to move inward in the X direction: 1680 x 1/8 = 210 

•

Amount to move inward in the Y direction: 1050 x 1/8 = 131 

The Calibrate Extended command then positions the first calibration target inward from 
the lower left corner (0,1049) and the second calibration target inward from the upper 
right corner (1679,0). The following illustration shows how the calibration targets are 
calculated for a Windows-based system. Your operating system may be different.