NEC LCD4020-BK-AV - 40IN LCD 1200:1 1366X768 60HZ Dvi-d... User manual

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External Control NECLCDMonitor
1. Application
This document defines the communications method for control of the NEC LCD monitor, MultiSync
LCD4020/4620/5220/6520 and MULTEOS M40/46 when using an external controller
.
2. Connectors and wiring
Connector: D-Sub 9-pin
Cable: Cross (reversed) cable or null modem cable
(Please refer “Using the LCD with RS-232C”on each User’s manual.)
3. Communication Parameter
(1) Communication system Asynchronous
(2) Interface RS-232C
(3) Baud rate 9600bps
(4) Data length 8bits
(5) Parity None
(6) Stop bit 1 bit
(7) Communication code ASCII
3.1 Communication timing
The controller should wait for a packet interval before next command is sent.
The packet interval needs to be longer than 600msec for the LCD monitor.

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4. Communication Format
The command packet consists of four parts, Header, Message, Check code and Delimiter.
Sequence of a typical procedure to control a monitor is as follows,
[A controller and a monitor, two-way communication composition figure]
4.1 Header block format (fixed length)
1
st
byte) SOH: Start of Header
ASCII SOH (01h)
2
nd
byte) Reserved: Reserved for future extensions.
On this monitor, it must be ASCII '0'(30h).
3
rd
byte) Destination: Destination equipment ID. (Receiver)
Specify a commands receiver’s address.
This value must match the “Monitor ID No.”set in the OSD.
Header Message Check Code Delimiter
Header
Message
Check code
Delimiter
SOH Reserved
'0' Destination Source Message Type Message Length
1
st
2
nd
3
rd
4
th
5
th
6
th
-7
th
MonitorController
Header
Message
Check Code
Delimiter
Header
Message
Check Code
Del
imiter
Get Parameter
Get Parameter Reply
Header
Message
Check Code
Delimiter
Set Parameter
Header
Message
Check Code
Delimiter
Set Parameter Reply
Header
Message
Check Code
Delimiter
Header
Message
Check Code
Delimiter
Get Parameter Reply
Save Current Setting Command
Get Parameter
Header
Message
Check Code
Delimiter
The controller sends command to
get a value from the monitor that
you want to change.
The monitor replies a current value
of the requested item.
The controller sends commands to
set an adjusted value.
The monitor replies to the
controller for confirmation.
The controller sends command to
get a value for confirmation.
The monitor replies an adjusted
value.
The controller requests to store
the adjusted value to the monitor.

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“Monitor ID”to “Destination Address”conversion table is as follows,
Monitor ID Destination
Address (ASCII)
Monitor ID Destination
Address (ASCII)
1 ‘A’(41h) 14 ‘N’(4Eh)
2 ‘B’(42h) 15 ‘O’(4Fh)
3 ‘C’(43h) 16 ‘P’(50h)
4 ‘D’(44h) 17 ‘Q’(51h)
5 ‘E’(45h) 18 ‘R’(52h)
6 ‘F’(46h) 19 ‘S’(53h)
7 ‘G’(47h) 20 ‘T’(54h)
8 ‘H’(48h) 21 ‘U’(55h)
9 ‘I’(49h) 22 ‘V’(56h)
10 ‘J’(4Ah) 23 ‘W’(57h)
11 ‘K’(4Bh) 24 ‘X’(58h)
12 ‘L’(4Ch) 25 ‘Y’(59h)
13 ‘M’(4Dh) 26 ‘Z’(5Ah)
ALL ‘*’(2Ah)
Ex.) If you want to control a monitor that has the "ID No." as '1', specify a destination address
'A'(41h). If you want to control all of the monitors which are connected by a daisy chain, specify
a destination address ‘
＊ ’(2Ah).
4
th
byte) Source: Source equipment ID. (Sender)
Specify a sender address.
The controller must be ‘0’(30h).
5
th
byte) Message Type: (Case sensitive.)
Refer to section 4.2 “Message block format”for more details.
ASCII 'A' (41h): Command.
ASCII 'B' (42h): Command reply.
ASCII 'C' (43h): Get current parameter from a monitor.
ASCII 'D' (44h): "Get parameter" reply.
ASCII 'E' (45h): Set parameter.
ASCII 'F' (46h): "Set parameter" reply.
6
th
-7
th
bytes) Message Length:
Specify the length of the message (that follows the header) from STX to ETX.
This length includes STX and ETX.
The byte data must be encoded to ASCII characters.
Ex.) The byte data 3Ah must be encoded to ASCII characters '3' and 'A' (33h and 41h).
 The byte data 0Bh must be encoded to ASCII characters '0' and 'B' (30h and 42h).
4.2 Message block format
“Message block format”is allied to the “Message Type”in the “Header”.
Refer to the section 6 “Message format”for more detail.
Header
Message
Check code
Delimiter

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1 ） Get current  parameter
The controller sends this message when you want to get the status of the monitor.
For the status that you want to get, specify the “OP code page”and “OP code”,
refer to “Appendix A. Operation code table”.
“Message format”of the “Get current
 parameter”is as follows,
 Refer to section 5.1 “Get current parameter from a monitor.”for more details.
2
） Get Parameter reply
The monitor will reply with the status of the requested item specified by the controller
in the “Get parameter message”.
“Message format”of the “Get parameter reply”is as follows,
 Refer to section 5.2 “Get parameter reply”for more details.
3
） Set parameter
The controller sends this message to change a setting of the monitor.
Message format of the “Set parameter”is as follows,
 Refer to section 5.3 “Set parameter”for more details.
4
） Set Parameter reply
The monitor replies with this message for a confirmation of the “Set parameter message”.
Message format of the “Set parameter reply”is as follows,
 Refer to section 5.4 “Set parameter reply”for more details.
5
） Command
“Command message”format depends on each command.
Usually, this “command message”is used for some non-slider controls and some special operations,
such as “Save current settings”, “Get timing report”, “power control”, “Schedule”, etc. Refer to
section 5.5 “Commands message”for more details.
6
） Command reply
The monitor replies to a query from the controller.
OP code page
OP code
STX Hi Lo Hi Lo ETX
Result OP code
page OP code Type Max value Current Value
STX Hi
Lo Hi
Lo
Hi
Lo
Hi
Lo
MSB
LSB MSB
LSB ETX
OP code
page OP code Set Value
STX Hi
Lo
Hi
Lo
MSB
LSB ETX
Result OP code
page OP code
Type Max value Requested setting
Value ETX
STX Hi Lo
Hi
Lo
Hi
Lo
Hi
Lo
MSB
LSB MSB LSB

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“Command reply message”format depends on each command.
Refer to section 5.5 “Commands message”for more details.
4.5 Check code
Check code is the Block Check Code (BCC) between the Header and the End of Message except SOH.
D
n+1
= D
1
XOR D
2
XOR D
3
XOR ,,, D
n
XOR: Exclusive OR
Following is an example of a Check code (BCC) calculation.
Check code (BCC) D
17
= D
1
xor D
2
xor D
3
xor …xor D
14
xor D
15
xor D
16
= 30h xor 41h xor 30h xor 45h xor 30h xor 41h
xor 02h xor 30h xor 30h xor 31h xor 30h xor 30h
xor 30h xor 36h xor 34h xor 03h
= 77h
4.6 Delimiter
Packet delimiter code; ASCII CR(0Dh).
Header
Message
Check code
Delimiter
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
SOH D
0
Reserved D
1
Destination D
2
Source D
3
Type D
4
Length D
5
STX D
6
Data D
7
| |
| |
ETX D
n
Check code D
n+1
P P P P P P P P
Header Message
SOH
Reserved
Destination
Address Source Address Message type Message length STX OP code page OP code Set Value ETX
Check
code
(BCC)
Delimiter
01
30 41 30 45 30 41 02 30
30
31
30
30
30
36
34
03 77 0D
D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
D
8
D
9
D
10
D
11
D
12
D
13
D
14
D
15
D
16
D
17
D
18
Header
Message
Check code
Delimiter

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5. Message type
5.1 Get current Parameter from a monitor.
Send this message when you want to get the status of a monitor.
For the status that you want to get, specify the “OP code page”the “OP code”, refer to
 “Appendix 
A. Operation code table”.
1
st
byte) STX: Start of Message
ASCII STX (02h)
2
nd
-3
rd
bytes) OP code page: Operation code page.
Specify the “OP code page”for the control which you want to get the status.
Refer to “Appendix A Operation code table”for each item.
OP code page data must be encoded to ASCII characters.
Ex.) The byte data 02h must be encoded to ASCII characters '0' and '2' (30h
and 32h).
OP code page 02h -> OP code page (Hi) = ASCII '0' (30h)
OP code page (Lo) = ASCII '2' (32h)
Refer to Operation code table. (Appendix A)
4
th
–5
th
bytes) OP code: Operation code
Refer to “Appendix A Operation code table”for each item.
OP code data must be encoded to ASCII characters.
Ex.) The byte data 3Ah must be encoded to ASCII characters '3' and 'A' (33h and 41h).
OP code 3Ah -> OP code (Hi) = ASCII '3' (33h)
OP code (Lo) = ASCII 'A' (41h)
Refer to Operation code table.
6
th
byte) ETX: End of Message
ASCII ETX (03h)
5.2 "Get parameter" reply
The monitor replies with a current value and the status of the requested item (operation code).
1
st
byte) STX: Start of Message
ASCII STX (02h)
2
nd
-3
rd
bytes) Result code.
OP code page
OP code
STX Hi Lo Hi Lo ETX
1
st
2
nd
-3
rd
4
th
–5
th
6
th
Result OP code page
OP code
Type Max value Current Value
STX
Hi Lo
Hi Lo Hi Lo
Hi
Lo
MSB
LSB MSB
LSB ETX
1
st
2
nd
-3
rd
4
th
–5
th
6
th
–7
th
8
th
-9
th
10
th
-13
th
14
th
-17
th
18
th

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These bytes indicate a result of the requested commands as follows,
00h: No Error.
01h: Unsupported operation with this monitor or unsupported operation under currentcondition.
This result code from the monitor is encoded to ASCII characters.
Ex.) The byte data 01h is encoded to ASCII character '0' and '1' (30h and 31h).
4
th
–5
th
bytes) OP code page: Operation code page.
These bytes indicate a replying item's OP code page.
This returned value from the monitor is encoded to ASCII characters.
Ex.) The byte data 02h is encoded to ASCII character '0' and '2' (30h and 32h).
Refer to the operation code table.
6
th
–7
th
bytes) OP code: Operation code
These bytes indicate a replying item's OP code.
This returned value from the monitor is encoded to ASCII characters.
Refer to the operation code table.
Ex.) The byte data 1Ah is encoded to ASCII character '1' and 'A' (31h and 41h).
8
th
-9
th
bytes) Type: Operation type code
00h: Set parameter
01h: Momentary
Like the Auto Setup function which automatically changes the parameter.
This returned value from the monitor is encoded to ASCII characters.
Ex.) The byte data 01h is encoded to ASCII character '0' and '1' (30h and 31h).
10
th
-13
th
bytes) Max. value: Maximum value which monitor can accept. (16bits)
This returned value from the monitor is encoded to ASCII characters.
Ex.) '0','1','2' and '3' means 0123h (291)
14
th
-17
th
bytes) Current Value: (16bits)
This returned value from the monitor is encoded to ASCII characters.
Ex.) '0','1','2' and '3' means 0123h (291)
18
th
byte) ETX: End of Message
ASCII ETX (03h)
5.3 Set parameter
Send this message to change monitor’s adjustment and so on.
The controller requests a monitor to change value.
1
st
byte) STX: Start of Message
ASCII STX (02h)
2
nd
-3
rd
bytes) OP code page: Operation code page
OP code page
OP code
Set Value
STX
Hi Lo Hi
Lo
MSB
LSB ETX
1
st
2
nd
-3
rd
4
th
-5
th
6
th
-9
th
10
th

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This OP code page data must be encoded to ASCII characters.
Ex.) The byte data 02h must be encoded to ASCII '0' and '2' (30h and 32h).
Refer to the Operation code table.
4
th
-5
th
bytes) OP code: Operation code
This OP code data must be encoded to ASCII characters.
Ex.) OP code 1Ah -> OP code (Hi) = ASCII '1' (31h)
OP code (Lo) = ASCII 'A' (41h)
Refer to the Operation code table.
6
th
-9
th
bytes) Set value : ( 16bit)
This data must be encoded to ASCII characters.
Ex.) 0123h -> 1
st
(MSB) = ASCII '0' (30h)
2
nd
= ASCII '1' (31h)
3
rd
= ASCII '2' (32h)
4
th
(LSB) = ASCII '3' (33h)
10
th
byte) ETX: End of Message
ASCII ETX (03h)
5.4 "Set parameter" reply
The Monitor echoes back the parameter and status of the requested operation code.
1
st
byte) STX: Start of Message
ASCII STX (02h)
2
nd
-3
rd
bytes) Result code
ASCII '0''0' (30h, 30h): No Error.
ASCII '0''1' (30h, 31h): Unsupported operation with this monitor or unsupported operation under
current condition.
4
th
-5
th
bytes) OP code page: Echoes back the Operation code page for confirmation.
Reply data from the monitor is encoded to ASCII characters.
Ex.) OP code page 02h -> OP code page = ASCII '0' and '2' (30h and 32h)
Refer to Operation code table.
6
th
-7
th
bytes) OP code: Echoes back the Operation code for confirmation.
Reply data from the monitor is encoded to ASCII characters.
Ex.) OP code 1Ah -> OP code (Hi) = ASCII '1' (31h)
OP code (Lo) = ASCII 'A' (41h)
Refer to Operation code table
8
th
-9
th
bytes) Type: Operation type code
Result OP code page
OP code
Type Max value Requested setting
Value
STX
Hi
Lo
Hi
Lo Hi
Lo
Hi
Lo
MSB
LSB MSB
LSB ETX
1
st
2
nd
-3
rd
4
th
-5
th
6
th
-7
th
8
th
-9
th
10
th
-13
th
14
th
-17
th
18
th

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ASCII '0''0' (30h, 30h): Set parameter
ASCII '0''1' (30h, 31h): Momentary
Like Auto Setup function, that automatically changes the parameter.
10
th
-13
th
bytes) Max. value: Maximum value that monitor can accept. (16bits)
Reply data from the monitor is encoded to ASCII characters.
Ex.) '0''1''2''3' means 0123h (291)
14
th
-17
th
bytes) Requested setting Value: Echoes back the parameter for confirmation. (16bits)
Reply data from the monitor is encoded to ASCII characters.
Ex.) '0''1''2''3' means 0123h (291)
18
th
byte) ETX: End of Message
ASCII ETX (03h)
5.5 Commands
"Command message format" depends on each command . Some commands are shown with usage. Refer to
section 7 to 10.
5.5.1 Save Current Settings.
The controller requests for the monitor to store the adjusted value.
 Send "OC"(30h, 43h) as Save current settings command.
 Complete "Save Current setting" command packet as follows;
ASCII: 01h-30h-41h-30h-41h-30h-34h-02h-30h-43h-03h-CHK-0Dh
SOH-'0'-'A'-'0'-'A'-'0'-'4'-STX-'0'-'C'-ETX-CHK- CR
The monitor replies the packet for confirmation as follows;
SOH-'0'-'0'-'A'-'B'-'0'-'6'-STX-'0'-'0'-'0'-'C'-ETX-CHK- CR
5.5.2 Get Timing Report and Timing reply.
The controller requests the monitor to report the displayed image timing.
 Send "07"(30h, 37h) as Get Timing Report command.
 Complete "Get Timing Report" command packet as follows;
ASCII: 01h-30h-41h-30h-41h-30h-34h-02h-30h-37h-03h-CHK-0Dh
SOH-'0'-'A'-'0'-'A'-'0'-'4'-STX-'0'-'7'-ETX-CHK- CR
The monitor replies status as the following format;
 SS: Timing status byte
Bit 7 = 1: Sync Frequency is out of range.
Bit 6 = 1: Unstable count
Command code
STX
'0' 'C' ETX
Command code
STX '0' '7' ETX
Command SS H Freq. V Freq.
STX
'4'
'E'
Hi Lo MSB
LSB
MSB
LSB
ETX

(10/40)
Bit 5-2 Reserved (Don't care)
Bit 1 1:Positive Horizontal sync polarity.
0:Negative Horizontal sync polarity.
Bit 0 1:Positive Vertical sync polarity.
0:Negative Vertical sync polarity.
 H Freq: Horizontal Frequency in unit 0.01kHz
 V Freq: Vertical Frequency in unit 0.01Hz
Ex.) When H Freq is '1''2''A''9' (31h, 32h, 41h, 39h), it means 47.77kHz.
5.5.3 NULL Message
The NULL message returned from the monitor is used in the following cases;
 A timeout error has occurred. (The default timeout is 10sec.)
 The monitor receives an unsupported message type.
 The monitor detects a packet BCC (Block Check Code) error.
 To tell the controller that the monitor does not have any answer to give to the host (not
ready or not expected)
 Complete "NULL Message" command packet as follows;
01h-30h-30h-41h-41h-30h-34h—02h-42h-45h-03h-CHK-0Dh
SOH-'0'-'0'-'A'-'A'-'0'-'4'-STX-'B'-'E'-ETX-CHK- CR
6. Typical procedure example
The following is a sample of procedures to control the monitor, these are examples of "Get parameter",
"Set parameter" and "Save current settings".
6.1. How to change the “Brightness”setting.
Step 1. The controller requests the Monitor to reply with the current brightness setting and capability
to support this operation. (Get parameter)
Header Message Check code Delimiter
SOH-'0'-Monitor ID-'0'-'C'-'0'-'6'
STX-'0'-'0'-'1'-'0'-ETX
BCC CR
Header
SOH (01h): Start Of Header
'0' (30h): Reserved
Monitor ID: Specify the Monitor ID from which you want to get a value.
Ex.) If Monitor ID is '1', specify 'A'.
'0' (30h): Message sender is the controller.
'C' (43h): Message type is "Get parameter command".
'0'-'6' (30h, 36h): Message length is 6 bytes.
Message
STX (02h): Start of Message
'0'-'0' (30h, 30h): Operation code page number is 0.
'1'-'0' (31h, 30h): Operation code is 10h (in the OP code page 0).
ETX (03h): End of Message
Check code
BCC: Block Check Code
Refer to the section 4.5 “Check code”for a BCC calculation.
Command code
STX 'B' 'E' ETX