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Line 1 6 0
S ots X o ff c h a ra c te r to [D C 3 ]C H R $ (1 9 ) .
Line 170
Sets the DTR pin to " High". In other words, does not allow the hardwire
handshake to operate.
Line 1000
Processes interrupt signals from the DXY-1000 series. The computer stops
to
the data transmission if [DC3] is sent and starts it again if [DC1] is sent
Line 1060
from the DXY-1000 series.
By setting Line 140 to line 170, the DXY-1000 series operates as follows;
(1) Outputs [DC3] as Xoff character if the remaining buffer capacity is below 150 bytes.
(The computer stops the data transmission.)
(2) Outputs [DC1] as Xon character it the remaining buffer character is over 5 12 bytes.
(The computer starts the data transmission.)
Remaining buffer capacity
In this program, the handshake is performed using interrupts under computer execution and
so does not work properly unless the computer has the ability to accept interrupts. If the in
terrupt works properly, the computer jumps from Line 1000 to Line 1080 and waits until the
next Xon signal is input if the interrupt signal is Xoff.
5.3.4 ENQ/ACK Handshake
In this handshake, the computer first sends the character specified as an ENO character to
the DXY-1000 series and asks whether it can transmit a certain amount of a data block. In
response to this, the DXY-1000 series tells whether data transmission is acceptable by the
character specified os an ACK character if the remaining buffer capacity is more than the
above block data amount.
Furthermore, the ENQ/ACK handshake is divided into three modes : mode 1. mode 2 and
dummy. Mode 1 is set by the ESC.H command, mode 2 by the ESC.I command and dum
my by the ESC.H command without any parameter.
In the dummy ENQ/ACK, especially if you do not set any ENQ or ACK character, the DXY-
1000 series returns the ACK character to the computer unconditionally when receiving the
ENQ character.
5 -1 2
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