6-8
commands are typically used for attached serial printers. Serial commands
cannot be combined with other commands in a message to the Base
Station/Terminal. Remember, you can only send 231 characters (including
the ID + @S + EOT).
SIGN ON
To login to the host computer, the user presses a key on the RF Terminal at
power-up to get to the SIGN ON screen. As the user SIGNs ON, the Base
Station sends back the following SIGN ON message to the host:
Byte position
Function
Possible values
1
RF Terminal ID
0-9, A-Z, a-z, - =
2+
SIGN ON
SYN (ASCII 22) if 6 line display
configured as a 6 line display.
SI (ASCII 15) if 6 line display terminal
configured as 4 line display.
Last Termination
of
message
CR (ASCII 13)
After a terminal SIGNS ON, the host should be prepared to acknowledge
the SIGN ON and give the terminal instructions, such as:
Standby for Assignment, Press ENTER to acknowledge
Nothing to do, Press ENTER and See Supervisor
Pick Item 1234
If there is something for the Terminal to do, the host should send instruction
to the terminal (as in “Pick Item 1234” above). If there is nothing to do at
the time of SIGN ON, the host should acknowledge the SIGN ON and tell
the terminal to
Stand By
or
See Supervisor
(see lines 1 and 2 above). You
will notice that in lines 1 & 2 above, there is a request for the operator to
press the ENTER key. This is required for the message to be a valid
command - remember that all messages must end with a request for data
input. The host should then expect a response from the terminal of
Terminal ID
+ DATA (none if only pressing ENTER key) +
CR
.
SIGN ON is a good way for the terminal operator who has not received
instruction from the host for several minutes to determine if he is still
connected and if the host is still functioning. By SIGNing OUT and
SIGNing back ON, the operator should receive a message that there is
nothing to do. It is also a good idea for the host to keep track of elapsed
time that a terminal has not had a message sent out to it. The host should
then send a message periodically to re-assure the operator (remember to ask
him to press ENTER) that instruction is coming or tell him to see his
supervisor for re-assignment (or whatever makes sense for your
application).
