Black Box ME375A-R2, User Manual

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CHAPTER 3: Installation
Table 3-1. Possible Settings of Internal Controls (cont’d.)
Callout Description Function/Label Possible Factory-
No. in Settings Default
Fig. 3-1 Setting
3 Clock-Source For master units, select INT INT
(CLOCK) either internal timing (INT) EXT
Jumper or external timing (EXT). LBT
For slave units, always select
loopback (received) timing
(LBT).
4 Local Enable/disable control of DIS DIS
Loopback local analog loopback EN
(LLB) testing with signals from
Jumper* the DTE
5 Remote Enable/disable control of DIS DIS
Loopback remote digital loopback EN
(RLB) testing with signals from
Jumper* the DTE
6 Chassis- Tie Signal Ground to Chassis CON CON
Ground (Protective, Frame) Ground DIS
(CHASS_ or isolate the two grounds
GND) from each other
Jumper
*Only connect the RLB and LLB jumpers (that is, set them to EN [enabled])
if you want to be able to turn local analog or remote digital loopbacks on
and off from the DTE using the proper RS-232 or V.35 signals. The settings
of these jumpers have no effect on the ANA and REM pushbutton switches
on the unit’s front panel; you will be able to control loopback testing with
those buttons whether these jumpers are connected or not. (There is no
way to control local digital loopback through the local DTE interface; you
must use the DIG button to do that.)