Kantronics MT1200, User Manual

Page: 65 / 157

Exiting TUP Mode
If you want to exit the TUP mode to "fine tune" parameter settings (or for any other
reason), the Command mode of the modem can be regained by using the transparent
data escape sequence, i.e., by sending a series of three control-Cs (unless a different
control character for COMMAND has been defined). (See TRANS command in the
Reference manual).
Poll Mode
Poll Mode Protocol Description
The POLL mode is generally used in system applications that implement a polled-
response protocol between a central site (Control Site) and one or more remote
locations (Remote Site). The POLL mode is similar to the TUP mode since it uses a
data transparent broadcast mode and a packet protocol with CRC-16 error-checking to
insure the integrity of the received data. All ASCII characters (hex 00 through FF) can
be transmitted and received. The POLL mode differs from TUP mode by allowing an
application program to address specific locations without changing any modem
parameters. All data sent by the application program at the central sit must begin with
the address (POLLID) of the intended remote modem. When any remote modem
receives data from the radio, the data is checked for errors and the received POLLID is
compared with its own POLLID. If they match, the POLLID is stripped and the data that
follows is sent to the serial port. All data received by the central site from the remote
location will arrive with the POLLID of the remote site automatically attached to the
beginning of the data.
It is the responsibility of the application program to: (1) address data to be sent to the
remote sites, (2) determine if the data was received, and (3) recognize responses that
contain the remote site's POLLID and data.
Digipeating is not allowed
Commands Used
Each modem is set up differently depending upon whether it is to be a Control modem
or a Remote modem.
Control Site
Control Site Configuration - The POLLID command in the Control modem must be set
to 0000 and the INTFACE command must be set to POLL. (See "Entering POLL Mode"
below.)
57