Comtech EF Data SDM-2020 - Manual (Page 133)

SDM-2020 Satellite Modulator Revision 7
ECL/HSSI TX MN/SDM2020M.IOM
10-12
10.1.5 M
ONITOR AND
C
ONTROL
F
UNCTIONS
10.1.5.1 S
YSTEM
I
MPLEMENTATION
Table 10-8. Signal Definition
Signal Definition
TA
(Data Terminal
Equipment
Available)
LA
(Loopback Circuit A)
LB
(Loopback Circuit A)
These signals are inputs from the HSSI interface. The state of these
inputs is read by the M&C from the ECL/HSSI interface status register.
CA
(Data
Communication
Equipment
Available)
LC
(Loopback Circuit C)
TM
(Test Mode)
These signals are outputs from the HSSI interface. The state of these
outputs is controlled by the M&C writing the ECL/HSSI interface control
registers.
TA This signal indicates the DTE is available for data transfers. When the
DTE is not available, the DTE status menu reflects DTE unavailable.
(Refer to Function Select Utility Interface menu.) If the DTE TX-IF CNTRL
is set to On (refer to Utility Interface menu for ECL/HSSI), the RF carrier is
On when TA is enabled, and the RF carrier is Off when TA is disabled.
The normal DTE-TX CNTRL setting is Off for most applications.
LA and LB loopback
input control signals
These signals are available to the M&C, but no functional support is
required.
Upon power-up, the CA output is set to UNAVAILABLE until all modem initialization
has been completed and no faults are detected. After completion of initialization the CA
line is set to AVAILABLE. Any detectable faults that cause the modem to be placed in a
non-operational mode will set CA to UNAVAILABLE.
TM output is set to ACTIVE if the ECL/HSSI interface is commanded into Loopback
mode. TM is INACTIVE for all other modes. LC output is not supported, and is set to
INACTIVE for all modes.