9
Switches S1 and S2: Gapped Clock
Switches S1 and S2 allow the Model 2042MT-MC to generate a
HSSI gapped clock. Gapped clocking is a method of flow control in
which data flow is interrupted by an idle (gapped) clock signal. In this
mode, the Model 2042MT-MC will gap the ST clock to the HSSI DTE
whenever the RS-530 CTS signal is de-asserted. In the ‘No Gapped
Clock’ setting, the RS-530 clock passes through with only a level
change.
S1
S2
Description
Off
Off
Not a Valid Setting
Off
On
Gapped Clock
On
Off
No Gapped Clock
On
On
Not a Valid Setting
Switches S3 and S4: Synchronization Method
Switches S3 and S4 allow the Model 2042MT-MC to compensate
for timing delays when transmitting HSSI data at high speeds (greater
than 2.5 Mbps). At high bit rates, set Switch S3 On and Switch S4 Off.
In this setting, the HSSI SD signal will be synchronized to the SD tim-
ing signal before conversion to RS-530. At lower bit rates (less than
2.5 Mbps), set Switch S3 Off and S4 On. In this setting, the RS-530
data bypasses the synchronization circuit and is passed straight
through to the HSSI DTE.
S3
S4
Description
Off
Off
Not a Valid Setting
Off
On
Data Skips Sync Circuit
On
Off
Data passes through sync circuit.
Off
Off
Not a Valid Setting
2042MT-MC DIP SWITCH SUMMARY TABLE
Position
Function
Factory Default
S1
Gapped Clock
On
S2
Gapped Clock
Off
S3
Sync Method
Off
S4
Sync Method
On
}
}
No Gapped
Clock
Bypass
Sync Circuit
10
4.0 INSTALLATION
The Model 2042 is designed to connect RS-530 devices to
devices which employ the HSSI interface standard. This section
describes how to install the units.
4.1 2042MC-MT CONNECTION
The Model 2042MC-MT is designed to connect an RS-530 DTE
device to an HSSI DCE device. In this application, the DB-25 (RS-
530) and HD-50 (HSSI) male connectors of the Model 2042MC-MT
may connect directly to their respective equipment ports, or they may
connect via a short “straight-through” cable (See Appendix C for
Interface Pin Assignments). Figure 7 below illustrates the proper con-
nection of the Model 2042MC-MT.
4.2 2042MT-MC CONNECTION
The Model 2042MT-MC is designed to connect an RS-530 DCE
device to an HSSI DTE device. In this application, the DB-25 (RS-530)
and HD-50 (HSSI) male connectors of the Model 2042MT-MC may
connect directly to their respective equipment ports, or they may con-
nect via a short “straight-through” cable (See Appendix C for Interface
Pin Assignments). Figure 8 below illustrates the proper connection of
the Model 2042MT-MC.
Figure 7. A Common RS-530 DTE to HSSI DCE Installation
Figure 8. A Common HSSI DTE to RS-530 DCE Installation
Router with HSSI
Interface
(DTE)
T1/T3 DSU with
RS-530 Interface
(DCE)
Model 2042MT-MC
Model 2042MC-MT
T1/E1 CSU/DSU with
HSSI Interface
(DCE)
T1/E1 Router with
RS-53 Interface
(DTE)
