Vidikron VP-42HD Manual Do Utilizador

80

Command 1
Unit ID 1
Unit ID 2
Command 2
Data length
Data
Check sum

Command 1
Command  1,  along  with  command  2,  is  a  number  used  to 
distinguish each command. In the case of ACK, when the lower 
order  4  bits  is  FH  (as  in  3FH  and  7FH),  this  indicates  that  the 
commands  and  data  of  the  supported  equipment  have  been 
received. When the lower order 4 bits is BH (as in 3BH and 7BH), 
this  indicates  that  unsupported  commands  and  data  have  been 
received.

Unit ID 1 and Unit ID 2
Unit  ID  1  and  unit  ID  2  are  numbers  used  to  identify  the 
equipment  that  is  to  be  connected.  60H  is  used  for  the  plasma 
monitor and 80H is used for external control equipment such as a 
personal computer. 
1) Unit ID 1: Indicates the equipment sending the signal
2) Unit ID 2: Indicates the equipment receiving the signal

Command 2
Command  2,  along  with  command  1,  is  a  number  used  to 
distinguish each command.

Check Sum (CKS), Error Processing, and ACK

1)  The check sum described below and RS-232C odd parity  
 

are used together for a check of the received data. The check  

 

sum is the lower order 8 bits of one frame of sent or received   

 

data comprising the sum total of Command 1, Unit ID 1 and 

 

2, Command 2, Data Length, and Data.

Check Sum Example

DFH

80H

60H

47H

01H

01H

08H

Com-

mand 1

Unit 

ID 1

Unit 

ID 2

Com-

mand 2

Data 

Length

Data

Check 

Sum

2) Error Processing
  * When the communication interval is vacant for more than 4  
  ms, thereafter a received Command 1 will be recognized. If, at  
  this time, meaningful data cannot be recognized, that data will  
  not be recognized (as valid data).
  * An ACK will not be returned unless the receive data error, the 
  check sum error, and the receive data are all taken in.