NEC NP-M311W Command Manual page 8

* Data portion
This becomes data of data length specified in the data length portion.
Command :
This sets data added to a command to send it.
( See each command description.)
Response :
This sets data added to a response to send it.
( See each command description.)
* Checksum
This is lower ranking 8 bits of the sum total of the header and data
portions of one transmit and receive data frame.
4-2. Data portion of response
**********************************************************************
For ACK
This returns ACK without adding data portion to the command that does
not request data.
This returns ACK with adding data to the data portion for the command
that requests data.
For NAK
This adds a cause of not accepting the command to data portion to
return it.
(Example) Power On
Command:
02H 00H FFH F0H 00H CKS
NAK:
A2H 00H 01H 20H 02H DATA01 DATA02 CKS
Data Contents
----------------------------------------------------------------------
DATA01 Error types
00H : Not supported
01H : Parameter error
02H : Operation mode error
03H : Gain-related error
04H : Logo transfer error
DATA02 Error description
* When not supported
00H : Unknown command
01H : The current model does not support this function.
02H : This model is not compatible with the Switcher.
03H : This model is not compatible with the PC Viewer.
* When a parameter error occurs
00H : Unvalid values specified.
01H : Specified terminal is unavailable or cannot be selected
02H : Selected language is not available.
* When an operation mode error occurs
00H : Available memory reservation error