NEC NDA-30115-001 User Manual
NDA-30115 Revision 1.0
Page 5
Property Management System - Communication Interface
Architecture
The control codes used for the message texts are:
Transmission
Protocol
Protocol
Before a message can be sent, a start sequence (also called a selecting sequence)
must be sent to urge the receiver to receive the data. Every transmission sequence
will begin with the sender sending a start sequence.
must be sent to urge the receiver to receive the data. Every transmission sequence
will begin with the sender sending a start sequence.
The start sequence is a three byte sequence:
Figure 2-1 Start Sequence
Table 2-2 Control Codes
Control Code
Hexadecimal
Value
Function
STX
02
Indicates the start of a block.
ETX
03
Indicates the end of a block.
EOT
04
Indicates the end of transmission of a block or release of the
data link by the sender.
data link by the sender.
ENQ
05
Used to query other party for expected response.
ACK
06
Indicates the positive acknowledgment of an information block
or start sequence.
or start sequence.
NAK
15
Indicates the negative acknowledgment of an information
block or start sequence.
block or start sequence.
DLE <
10, 3C
Indicates the receiver interrupting to ask for sending rights.
DLE :
10, 7C
Indicates the receiver interrupting to ask the sender to stop
transmission and to release the data link.
transmission and to release the data link.
DLE ?
10, 3F
Used as the negative acknowledgment of block and indicates
that the receiver temporarily cannot receive data from the
sender.
that the receiver temporarily cannot receive data from the
sender.
05H
‘1’
‘!’
0
1
2
SA
UA
ENQ