Worth Data RF Terminal 7000 - Manual (Page 33)

back and forth as described in example 1. The Base Station sends a data prompt to the RF Terminal, the RF
Terminal transmits the operator-entered data back to the Base Station. If the host program has another
prompt for the terminal, the Base sends it out, repeating the process above.
Suppose the host program does not have a prompt ready to send back to the Terminal; the Terminal
transmits its data to the Base Station but does not receive a new data prompt. The Terminal then retransmits
its data (it thinks maybe the host didn’t receive it) and waits for a response.
Once the terminal has received a prompt back from the host, the time it took the host to respond is sent to
the Terminal. For all subsequent transmissions, the terminal goes to sleep until the time it took the last time
for the host to respond has expired; then the terminal wakes up and listens. If it has nothing, it retransmits its
data and waits for a response.
The original data transmission could have collided with another message, or the Base could have received
the Terminal's data but had not yet received the host's prompt response. If the previous transmission got
through, the Base Station knows that the data is a retransmission rather than a new data transmission so it
sends a message to the Terminal telling it:
“I have nothing for you from the host, go to sleep”.
While in “sleep” mode, the Terminal “wakes” up at a random interval and asks “do you have anything for
me yet”, waiting for either a “go to sleep” message or a new data prompt. After each delay, the Terminal
displays:
WAITING FOR HOST PROMPT
If a Terminal receives no response at all from a Base Station (no data prompt or “go to sleep” message), it
retransmits its data and waits for a response. If the Terminal gets no response after 10 re-transmissions, it
assumes it is out of range from the Base Station with which it was communicating, and attempts to establish
contact with any Base Station. If the Terminal can't contact any Base Station, it displays:
TRANSMISSION FAILED
HIT ANY KEY_
Pressing a key on the Terminal starts the re-transmission process over again. The RF Terminal will try to
retransmit its data, displaying the TRANSMISSION FAILED message after every 10 unsuccessful tries.
Can I change a prompt after it has been sent?
Normally once the Terminal has received a prompt from the host, it goes to sleep and waits (as long as it
takes) for the operator to scan or key something in response. The host cannot send another prompt without
creating a "Sequence Error." You might want to change the prompt or locate a lost terminal with beeping.
There is a special setting in the RF Terminal Setup in which you specify the time (between 5 seconds and 7
minutes) you want the Terminal to quit waiting for input from the operator, blank the screen, send back a
special control character to the host program, display "Waiting on Host Prompt" and wait for a prompt from
the host application program; the host application program can choose to send back different instructions or
simply repeat the previous prompt's instructions, (See Automatic Check Back in the Programming Section).
How the One-Way RF System works
The RF System can be used to perform “dumb” data entry to the computer – you could even use PortKey to
transmit the data through a serial connected Base as though it has been entered from the keyboard. This is
useful if you want to enter data directly into an application. This type of data transmission is called One-Way
Mode. Once the RF Terminal transmits data to the Base Station, the Base Station acknowledges receipt of the