HP 7470A Interfacing And Programming Manual page 163

0 Enquiry character (ESC . I or ESC . H command)
0 Acknowledgment string (ESC . I or ESC . H command)
In its simplest form, the data exchange looks like this:
DO YOU HAVE BUFFER SPACE FOR A DATA BLOCK'
"ENO"
YES, THERE IS ROOM IN MY BUFFER
COMPUTER < PLOTTER
"ACK"
DATA
ENQ/ACK Handshake Protocol Example 1
In a more complex form, the communication might look like the
following example, where the two commands . M250;17;10;13:
and . H100;5;6: have been sent to specifythe variables as:
turnaround delay = 250 ms
outputtrigger character = ASCII character DC1 (decimal equiva­
lent 17)
echo terminate character = ASCII character LF (decimal equiva­
lent 10)
output terminator = ASCII character CR (decimal equivalent 13)
data block size = 100 bytes
enquiry character = ASCII character ENQ (decimal equivalent 5)
acknowledgment string = ASCII character ACK (decimal equiva­
lent 6)
RS-232-CCCITT/V.24 INTERFACING 10-21