Comtech EF Data SFC4200 - Manual (Page 57)

SFC4200/SFC1275G Synthesized Frequency Downconverter Electrical Interfaces
TM054 - Rev. 4.0 5-7
Figure 5-5. Full-Duplex RS-485 Serial I/O Configuration
Figure 5-6. Half-Duplex RS-485 Serial I/O Configuration
To prevent data collisions from all the converters responding at once, each converter must be
software configured for ‘echo off’ in the Configuration Menu. If the converters are being linked to
a dumb terminal, the echo should be turned on locally.
5.10 Coarse VCXO Adjustment
This adjustment at the rear panel is used to set the initial accuracy of the 10 MHz reference. The
coarse adjustment was factory-set to 1 x 10
-9
accuracy with the software offset set to 000 PPB.
Refer to Section 4.2.10.2 for the software fine adjustment feature. When the fine adjustment
approaches
±
999 PPB, a coarse adjustment may be necessary.