Troubleshooting The Physical Layer; Selecting Functions With Dip Switches Sw1-1 Through Sw; Selecting Functions With Dip Switches Sw2-1 Through Sw - Comdial DXP Plus Manual

IMI89–207
2

Troubleshooting The Physical Layer

SW1, SW2, and the LIU switches must be set up according to the customer's requirements. See Installing
The DXPT1 Digital Carrier Transmission Option, IMI89–193 for directions.
2.1

Selecting Functions With DIP Switches SW1-1 Through SW1-8

NOTE: SW1 switch contents will be updated only during a reset operation.
The mode, superframe or extended superframe, is critical. If set wrong, the board will not find frame sync
causing the red Sync LED to light.
Yellow alarm mode (SW1-4) is always off, unless the customer is in Japan.
Suppression is defaulted to B7. If digital data is ever presented to the DXPT1 board from a drop and
insert multiplexer (mux), or any other means, B8ZS will be required even though the channel is disabled
in the DXP Plus. The digital data could be all zeros violating the ones density requirement of 1 in 8 bits in
a channel. The network or mux must also have B8ZS enabled. If B8ZS is being sent in any channel the
green LED above SW1 will flicker if SW2-6 is enabled. Do not set SW1-5 and SW1-6 to the "no
suppression" setting unless approved by Comdial Engineering. The "no suppression" setting is for
possible future needs.
SW1-7 and 8 are critical to the channel capacity required.
2.2

Selecting Functions With DIP Switches SW2-1 Through SW2-8

SW2-1 is valid only in the superframe mode. This switch must be "on" if the network is capable of
initiating an inband loopback. The switch will not cause a remote loopback but it will look for the
command from the network. Leaving the switch "on" does not hurt anything whether the network can
perform the loopback operation or not. A reset is not required when changing the switch.
SW2-2 is programmed at reset in the ESF mode only, and it will always be "off" (default) unless the
network requires the facility data link messages to be a different ID. The default is customer premise
equipment. If the network requests that the messages have a carrier-type header ID, turn the switch "on"
and reset the board. This will probably never need to be "on".
SW2-4 is for reporting CRC errors in the ESF mode, if the network has the ability to support the CRC
feature. The default position is "off" to prevent false errors when the error checking is not supported by
the network.
SW2-5 is to allow or prevent the sending of facility data link message packets in ESF mode during a
preemptive yellow alarm and loopback messages. The ANSI specification allows FDL packets to be
stopped during a yellow alarm and loopback, but some customers/networks want the packets to continue.
Switch changes require a reset to be programmed.
SW2-6 defines the meaning of the green LED labeled "B8ZS/COFA." A reset is not required when
changing this switch. When the switch is "off" (default), the LED indicates COFA detected. When the
switch is "on," the LED indicates B8ZS detected. B8ZS detection is handy to verify if the network is
sending B8ZS. If so, and the B8ZS suppression is not set (SW1-5, 6), the B8ZS will be seen as bipolar
alarms, and recorded as such, even though they are not,
SW2-7, 8 are manual loopback requests for diagnostic reasons. Local loopback verifies the ability of the
DXPT1 to sync on itself to insure frame syncing problems are not caused by the DXPT1 board. These
switches are rarely used to enable remote loopback and payload loopback.
NOTE: A local loopback will disable the synchronization card reference causing an automatic switch to
the next reference. If only one reference is configured, the system defaults to the DXP Plus fixed
oscillator on the services board.
8 – Troubleshooting The DXPT1 Installation
Troubleshooting The DXPT1 Installation