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MDR-2000
V3
User's Reference Manual
Communications
XT
- The 'Transmit' command sends the record
at
the current buffer pointer location in the cur-
rently selected data storage buffer. This record is encapsulated in the protocol described in the next
section.
An
'END'
message is returned when the buffer is empty or the pointers have been
advanced past the last record in the buffer by the
'OK'
command.
19
-
Sets the modem and PBX port baud rates to 19200 temporarily. This command is used for
automated testing
of
the MDR-2000. The
MR
command causes them to reset to their previous
values.
4.2 Protocol
The MDR-2000 utilizes protocols to ensure the integrity
of
the data transmitted to the host system.
There is no protocol used between the MDR-2000 and the various PBXs. The following
paragraphs describe how the collection process should be handled by any third-party utility that
is
designed to download data from the MDR-2000. The process described is for transferring data a
single record at a time. Refer to the section on 'Large Blocksize Polling' for details on
downloading multiple records per transfer request.
The first level
of
protocol applies to the coordination
of
communications between the MDR-2000
and the host system. This protocol is basically summarized
by
the fact that the MDR-2000 trans-
mits data only when requested by the host. The MDR-2000 never initiates data transmission. Even
when it dials the host system for alarm conditions the host must initiate the transmission
of
data.
In some cases proper reception
of
commands from the host
to
the MDR-2000 must be inferred. For
example,
ifthe
'ID' message is returned, then one can safely infer that the
'ID'
command was
properly received by the MDR-2000.
A more difficult situation is the
'OK'
command. To ensure its correct reception the previous record
transmitted as the result
of
an
'XT'
command must be compared to the current record transmitted.
If
they are different then it is a proper assumption that the
'OK
' command was properly received
and processed by the MDR-2000.
There are some commands for which proper reception cannot be inferred. These are the
'XT'
and
the
'CL'
commands. To ensure accurate communications with the MDR-2000 these commands
return values, encapsulated in a data packet.
This second level
of
protocol, which uses the data packet, applies to the transmission
of
call records
from the MDR-2000 to the host system only. In addition, the
'CL'
command responds with a
'CLR'
message which is also sent as a data packet.
4-5
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