H5: Protocol logic
Parameter value Meaning
0
Combination of 1 and 3 below
1
DTR/DSR, positive logic
2 DTR/DSR, negative logic
3 XON/XOFF
4
ETX/ACK
5
XON/XOFF recognized only as protocol
The factory setting is 0.
H6: Buffer nearly-full threshold
This is a percentage from 0 to 99. The factory setting is 90.
H7: Buffer nearly-empty threshold
This is a percentage from 0 to 99. The factory setting is 70.
The factory settings of the buffer nearly-full and nearly-empty thresholds (H6 and H7) are sub-
ject to change without notification.
The gap between the nearly-full and nearly-empty thresholds allows the computer to send a
fairly large amount of data in a continuous stream.
H8: Received-data buffer size
This is the size of the input buffer, specified in units of 10K bytes. The factory-set value is 6
meaning 60K bytes.
☛ Since DTR/DSR protocol is not used with the RS-422A standard, select a pa-
rameter value other than 0, 1, or 2 for the H5 setting when using the RS-422A
interface.
PRESCRIBE II FRPO D0 command
The PRESCRIBE II FRPO D0 command is provided to allow manipulating XON/XOFF when an er-
ror has occured on the serial interface. The following table summarizes the error status corre-
sponding to different D0 values.
Serial interface error
error not handled error handled
Timing of XON transfer
to host while Ready or
Waiting
XON sent every 3-5
seconds
D0 = 0 (default) D0 = 1
XON not sent D0 = 10 D0 = 11
C.3. RS-232C/RS-422A Protocol
C-11