9-92 2x20 Customer Display Interface
Reset Display
Format
1B 01
Returns
xx yy zz
• where xx is the Microcontroller status:
00 = OK
If a failure occurs, testing halts, and the firmware begins executing a loop as described
in the Internal Power UP Diagnostics section in the Installation chapter.
• where yy is the External Character PROM status:
00 = Not present (Always 00 for LCD)
01 = OK, present
FF = Failure
• where zz is the number (in hex) of character sets available in the External Character
PROM
00 = 10 (Always 00 for LCD)
Description
This command executes the power-down power-up diagnostic sequence. The
communication lines (CTS for serial, BUSY for parallel) are placed in an exception
condition (see the Internal Power UP Diagnostics section in the Installation chapter). The
Microcontroller test consists of a check-sum test on the ROM and a write/read test on
the RAM. A check-sum test is also performed on the External Character PROM that
holds any user-defined characters sets (This does not apply to the LCD).
After executing the command, the three status bytes (see above) are sent to the host, the
display screen is cleared, the cursor moves to the 0 position, communication line
exception conditions are cleared, and all registers and variables are initialized. Note that
the screen is cleared during this command. If a host needs previous data redisplayed,
the host must resend the previous data after this command has completed.
Erase Display
Format
1B 02
Description
This command clears all of the displayed characters by writing a space to each display
position. A space is defined as character 0x20 of the current character set. The cursor
moves to the 0 position.
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