Mitel SX-200 Practices page 1169

m .
DATASET
2100
Series Description
connection, it cannot signal to the other; the PABX must drop this connection with a
Terminate B channel command, which it can do because the D channel is active
while the B channel session is in progress.
Data is clocked to and from the shift registers at a constant rate by the synchronous
clocks on the W-232 interface. The data set firmware converts this data into packets
which are passed through the PABX in Ul frames. No error detection or correction is
performed on this data; synchronous data usually includes its own error detection and
correction protocol, and it is more important to maintain the synchronization between
the two endpoints. The synchronization is done by a software Phase Locked Loop
algorithm, which actually becomes a frequency locking loop.
X.31 - It is a protocol for adapting a data rate from a synchronous interface to a 64 kbps
channel, such as is used by MITEL PABXs. This mode will allow Mite1 equipment to be
connected to another manufacturer's equipment without having protocol conversion in
between. The synchronous data being received must be HDLC based, with a maximum
frame size of 512 bytes,
The DATASET 2100 decodes the received HDLC frames and reformats them into new
HDLC frames using the X.31 protocol on the B channel. The rate conversion is done
by transmitting HDLC flags during B channel idle time. Received frames are
depacketized and transmitted to the attached device in HDLC format at the W-232
interface synchronous clock rate,
Asynchronous Operation
j5.4 The DATASET 2100 Series can operate in asynchronous mode in simplex, half
duplex, or full duplex modes. Once the communications are established between
data sets in asynchronous mode, the D channel connection is dropped, and only the
B channel connection remains. The B channel passes through the PABX, without
supervision by the PABX, connected only to the two endpoints.
Back-b-Back Operation
15.5
Two DATASET 2100 Series may be connected back to back to communicate directly
with each other (typically to bypass a failed PABX). At least one of the data sets must
be in hunt mode; the data set then alternates between master and slave timing until
synchronization is achieved. If both data sets are in hunt mode, it can take up to one
minute to achieve synchronization.
A back to back connection may be established as above in either synchronous mode
or in asynchronous mode between two DATASET 2100 series. If the DATASET 2100
Series is in master mode and asynchronous mode, the back to back connection can
also be made with a DATASET 1100 series. The data set that is operating in master
mode scans its DIP switches on power up, and sets its operating parameters according
to the settings of the switches.
9109-09&126-NA
Issue
1
Revision
0
126 15-3