5
3-2-2. Response data packets from the RT-20 to the HOST
The RT-20 can respond to the HOST in a synchronous and asynchronous mode. The two different response
packets are described below.
3-2-2-1.
ACK/NAK Response Packets
The RT-20 provides an ACK (acknowledge) response to the HOST when the RT-20 has received a correct
command packet, and the HOST command packet has requested no other status data.
Start character
: ’@’,
ACK
: 06h,
End character (CR) : 0Dh
The RT-20 will send a NAK response packet if the RT-20 has received an incorrect HOST command packet.
Start character
: ’@’,
NAK
: 15h,
End character (CR) : 0Dh
3-2-2-2.
Auto Status Feedback Packets
The RT-20 will send to the HOST asynchronous status feedback data packets when applicable RT-20 status
changes. The asynchronous status has been divided into levels or groups. The HOST can enable each of the
status feedback groups independently.
Start character
: ’@’
Answer character
: see “Status Feedback” on page 14
End character (CR) : 0Dh
End
0D h
Status answ er
Start
‘
@
’
A C K
06h
C R
0D h
start
‘
@
’
N A K
15h
C R
0D h
start
‘
@
’
