ViewSonic CD4220 User Guide - Page 55

Get-Function Listing

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6.2 Get-Function Listing The PC can interrogate the LCD Monitor for specific information. The Get-Function packet format consists of 5 bytes which is similar to the Set-Function packet structure. Note that the "Value" byte is always = 00. Get-Function description: Length: Total bytes of message = 5 ASCII (35H), excluding "CR" Command: Get-Function command code: One byte ASCII code Value[1~3]: Always = 000 Get-Function format from PC to LCD (ASCII) Name Length Command Value1 Value2 Value3 CR Byte Count 5 1 Byte 0 0 0 00D Bytes order 1 2 3 4 5 6 Monitor shall response to Get-Function with the following packet format: LCD Monitor response packet format: Name Length Value1 Value2 Value3 Value4 CR Byte Count 5 1 Byte 1 Byte 1 Byte 1 Byte 00D Bytes order 1 2 3 4 5 6 Response packet (to Get-Function): Length: Total bytes of packet = 5 ASCII excluding "CR" Exception: Total bytes for On-Hours = 6 Value[1-4]: Four ASCII codes: Value range is from 0000 ~ 9999 Exception: Value[1-5] for On-Hours LCD Monitor will send "+" (02Bh), "CR" bytes to PC after receiving a valid command LCD Monitor will send "-" (02Dh), "CR" bytes to PC if the command is not valid ƒ The following is an example of PC requesting the volume value from the LCD Monitor: PC send Get-Volume-value packet to Monitor (In ASCII) Name Length Command Value1 Value2 Value3 CR Byte Count 5 f 0 0 0 00D Bytes order 1 2 3 4 5 6 LCD Monitor will send "-" (02Dh), "CR" to PC if command is not recognized. Otherwise the LCD Monitor will respond with the volume value as outlined below: LCD-Monitor response packet to Get-volume-value (in this example the volume value is 50): Name Length Value1 Value2 Value3 Value4 CR Byte Count 5 0 0 5 0 00D Bytes order 1 2 3 4 5 6 A special command "Get-ACK" is used to test the communication link between PC and the LCD Monitor. The LCD Monitor shall response to "Get-ACK" command with a "+" or "-". Get-ACK from PC to LCD (ASCII) Name Length Command Value1 Value2 Value3 CR Byte Count 5 z 0 0 0 00D Bytes order 1 2 3 4 5 6 LCD Monitor will send "+" (02Bh); "CR" bytes to PC after receiving the command indicating that the communication link is OK ViewSonic CD4220 53

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6.2
Get-Function Listing
The PC can interrogate the LCD Monitor for specific information. The Get-Function packet format
consists of 5 bytes which is similar to the Set-Function packet structure. Note that the “Value” byte is
always = 00.
Get-Function description
:
Length:
Total bytes of message = 5 ASCII (35H), excluding “CR”
Command:
Get-Function command code: One byte ASCII code
Value[1~3]:
Always = 000
Get-Function format from PC to LCD (ASCII)
Name
Length
Command
Value1
Value2
Value3
CR
Byte Count
5
1 Byte
0
0
0
00D
Bytes order
1
2
3
4
5
6
Monitor shall response to Get-Function with the following packet format:
LCD Monitor response packet format:
Name
Length
Value1
Value2
Value3
Value4
CR
Byte Count
5
1 Byte
1 Byte
1 Byte
1 Byte
00D
Bytes order
1
2
3
4
5
6
Response packet (to Get-Function)
:
Length:
Total bytes of packet = 5 ASCII excluding “CR”
Exception: Total bytes for On-Hours = 6
Value[1-4]:
Four ASCII codes: Value range is from 0000 ~ 9999
Exception: Value[1-5] for On-Hours
LCD Monitor will send “+” (02Bh), “CR” bytes to PC after receiving a valid command
LCD Monitor will send “-” (02Dh), “CR” bytes to PC if the command is not valid
±
The following is an example of PC requesting the volume value from the LCD Monitor:
PC send Get-Volume-value packet to Monitor (In ASCII)
Name
Length
Command
Value1
Value2
Value3
CR
Byte Count
5
f
0
0
0
00D
Bytes order
1
2
3
4
5
6
LCD Monitor will send “-” (02Dh), “CR” to PC if command is not recognized.
Otherwise the LCD Monitor will respond with the volume value as outlined below:
LCD-Monitor response packet to Get-volume-value (in this example the volume value is 50):
Name
Length
Value1
Value2
Value3
Value4
CR
Byte Count
5
0
0
5
0
00D
Bytes order
1
2
3
4
5
6
A special command “Get-ACK” is used to test the communication link between PC and the LCD Monitor.
The LCD Monitor shall response to “Get-ACK” command with a “+” or “-“.
Get-ACK from PC to LCD (ASCII)
Name
Length
Command
Value1
Value2
Value3
CR
Byte Count
5
z
0
0
0
00D
Bytes order
1
2
3
4
5
6
LCD Monitor will send “+” (02Bh); “CR” bytes to PC after receiving the command indicating that the
communication link is OK
ViewSonic
CD4220
53