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3M™ Display M2256PW User Guide
3M Touch Systems, Inc. Proprietary Information
where:
Tt
= Two ASCII characters that identify the controller type.
AD
Indicates the PX series of controllers
Ffff
= Four ASCII characters that indicate the features supported by the
controller.
**** Indicates no additional features configured
Ss
= Two ASCII characters that provide status information about the
controller hardware. The two characters represent one byte. Each
character is in the range 0 to 9 and A to F.
Table 2 defines the meaning of each bit in the status byte. Each bit
can be set to 1 or 0, where
1
= an error and
0
= no error. So a
response of:
00
= No diagnostic errors (normal response)
The PX running with no errors returns the following string:
<SOH>
AD****00
<CR>
The format includes two bitmapped ASCII hex status bytes. A “00” indicates no errors.
Table 19 Bit Meanings in Status Byte
Bit
Description
Notes
0 Not
used
1
ROM_ERROR
Code area checksum error
2
PWM Error
Touch screen not connected or potential problem.
3
NOV_ERROR Parameter Block1 checksum error
4
HDW_ERROR
Problem with ADCs
5
Not used
6
Not used
7
Not used
Touch Data Format
The format is a six byte packet that includes one status byte, four bytes of binary X,Y
position data and a touch ID. The X,Y coordinates are 14 bits, providing a range of 0 to
16,383. The data is sent in the following format: