Comtech EF Data SMS-758 - Manual (Page 47)

SMS-758 Modem Protection Switch Operation
MN/SMS758 Rev. 3 3–9
The operator can view the modem configuration parameters by using the [NEXT] and
[PREV] keys. A flashing cursor will be displayed over the selected parameter. To enter
data or change a parameter, the operator uses the keypad to enter the data. When all data
or changes for that parameter are correct, press [ENT] to load the information into
memory. The following sections describe each parameter in detail.
Note: [ENT] or [NEXT] may be used to get from one frame to the next in this menu, but
only [ENT] will enter data.
3.2.2.1 Interface Type Menu
This menu displays the current interface type for each prime and backup modem.
Selections 1 through 9 are labeled:
Screen 1 1. 15D (For both DS-1 and G.703 interfaces)
2. V.35
3. RS449 (For both RS-422/449 and MIL-STD-188-114/RS-449 interfaces)
Screen 2 4. DCTN (Modified RS-422 interface)
5. IDR (for 1:N AS/0895)
6. OTHER
Screen 3 7. IBS
8. D&I (for “loomed” D&I systems. Read paragraph below.)
9. IDR 2:N (for 2:N AS/1877)
The operator enters the number associated with the interface type, and presses [ENT] to
load the selected interface information into memory. Selections may only be made from
the displayed options. If no interface type is entered for an active modem, an M:N fault
results.
The OTHER interface type applies to ASYNC interfaces (AS/1695), or installations with
dual 1:4 systems, or similar configurations having identical interfaces. Normally, the
switch treats the two 1:4 systems with the same interface type as a single 2:8, but when
OTHER interface type is selected for one of the 1:4 systems, the switch considers the
interfaces different, and treats each 1:4 system as a separate system.
The “loomed” D&I system requires special firmware in the switch, special switch
interfaces (AS/2152), additional breakout panels, and special cabling. The advantage of
the “loomed” system is that during switching, there is no interruption of the data stream
(T1 or E1). The only data that is affected is the data of the failed unit.
Note: Interface type is the only setup parameter for backup modems.
Note: Although the last three options do not exist with modem switch firmware, IBS and
IDR 2:N can be chosen by selecting option 6 (OTHER).