CTI Products IOB I/O Interface - Manual (Page 30)

IOB Hardware Reference System Examples
CTI Products, Inc.
68-11168-105
25
7.3 Inverted Select A Example
For this example, assume we have the same system as in section 7.2, but we need
to changed the system so that the TX 1 Select relay is normally closed (so that if
the power fails, the TX 1 Select relay will be engaged). Figure 8 shows this
modified system drawing.
COM 2
COM 1
CA-80223-100
HIB
T
P/S
IN
OUT IN
OUT
T
IOB
CIRCUIT
USER APPLICATION IOB
CIRCUIT
PTT4
PTT3
PTT2
PTT1
TX 1 SELECT
TX 2 SELECT
TX 3 SELECT
TX 4 SELECT
LOCAL PC
Figure 8 - Inverted Select A Example
Because the Select 1A output is connected to a normally closed relay, we need the
Select 1A output to operate as an active high output instead of active low. The
Select 1A output should be high when the Select 1A output is not the selected
output and low when the Select 1A output is the selected output. The OPTION
switch position 3 needs to be placed in the UP position to enable the inverted
Select A output mode (the module must be reset or power cycled after the switch
is changed).
The system in Figure 8 operates the same as the system in section 7.2