4
3. Detailed
Description
The RS-232 hardware interface specification between the HOST and the RT-20 is described below.
3-1. Connection format
3-1-1. Physical connection
HOST
RT-20
(Serial Port settings)
Baud Rate : 9600bps
Data Bits : 8bit
Parity : None
Stop bit
: 1bit
Handshaking : None
3-2. Transmission data packet formats
3-2-1. Transmission data packets from the HOST to the RT-20
There are two kinds of transmission data packets that are described below.
3-2-1-1.
Command Packets
The Command Packets are provided for the Host Controller to request the RT-20 to perform a specific action.
Start character
: ’@’
COMMAND
: see “Data Packet COMMAND List”on page 16
End character (CR) : 0Dh
E nd
0D h
C O M M A N D
S tart
‘
@
’
3-2-1-2.
Status Request Packets
The Status Request packets are provided for the Host Controller to request the RT-20 to report specific
operating statuses.
Start character
: ’@’
Request status
: see “Status Request and Status Response Data Packets” on page 11
Request character
: ‘?’
End character (CR) : 0Dh
E nd
0D h
R equest status
S tart
‘
@
’
1
9
‘
?
’
TxD
RxD
GND
RxD
TxD
GND
