7700 MultiFrame Manual
7707IT Multi-Channel Intercom Fiber Transceiver
Revision 1.7
Page - 23
CTRL
To turn the termination on or off, select the
CTRL
menu item in menu level
1. Use the toggle switch to choose the channel to which the termination will
be applied. Press the pushbutton to apply the displayed selection.
CH01
to
CH08:
Range of channels for the 7707IT-8.
CH01
to
CH03:
Range of channels for the 7707IT-3.
Use the toggle switch to select the
TERM
menu item and press the
pushbutton. The toggle switch may then be used to turn the termination on
or off. Use the toggle switch to select the desired state then press the
pushbutton to apply the displayed selection and return to menu level 3. You
can select other items on menu level 3, or select the
BACK
menu item to
return to menu level 2.
ON:
The 110
Ω
is selected as active.
OFF:
The 110
Ω
is selected as inactive, and the input is
high impedance.
The factory default configuration turns the termination
OFF
. Changing the
interface profile will restore the factory default termination state for the
respective channel(s).
CH01 to CH03 or
CH08
TERM
ON
OFF
4.2.9. Selecting the Serial Data Failsafe Bias
To simplify installation, the 7707IT provides a selectable failsafe bias for balanced serial data signals. This
bias should be active as required by the specific application, and common practice. The failsafe bias will
apply a differ200mV bias to a properly designed RS-485 system while in the idle state. As a
protection feature, the failsafe bias will not become active unless the termination is also active for the
respective channel. The failsafe bias circuit of the 7707IT will function properly over the specified input
common mode range. Selection of the failsafe bias is done using the card-edge interface or through
Vista
LINK
®
control.
