Manual

5-6 RS-232C Communications
Example: the sequence ESC.I;5;6:ESC.M10: sets up a "normal" ENQ/ACK handshake
using the ASCII characters ENQ and ACK, with a 10 millisecond turnaround delay.
Software Checking Handshake
The Software Checking handshake works as follows. The host repeatedly sends the ESC.B
command to the Automove System, effectively asking "how much room do you have in your
buffer?" The System sends back a number giving the available buffer space. When the
number is at least equal to the size of the block to be transmitted, the host sends the block of
data. This sequence repeats until all data have been transmitted.
Because of the great number of characters transmitted in each direction, the Software
Checking handshake significantly slows down system throughput. It should only be used in
cases where none of the other three handshakes can be made to work. See Appendix F
Choosing A Handshake.
The host need take no specific action to begin using the Software Checking handshake.
Other communications parameters which may need to be changed for the handshake to work
successfully are: Turnaround Delay (
ESC.M), Output Trigger Character (ESC.M), Echo
Terminate Character (
ESC.M), Output Initiator Character (ESC.M), Output Terminator
(
ESC.M), and Intercharacter Delay (ESC.N).
Dummy ACK
In order to facilitate startup of the handshake in hosts which must use the Enq/Ack
handshake, the Automove System supports a Dummy ACK response. If no Enq/Ack
handshake is active, or if the <Enquiry Character> is not an ASCII ACK (character code 6),
the Dummy ACK is enabled. In this case, whenever the Automove System receives the
ASCII ENQ character (character code 5), it immediately transmits the ASCII ACK character
(character code 6). This is not a handshake and will not prevent buffer overflow.
For more information about the different handshake types, please see Appendix F Choosing
a Handshake.