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Operational Verification
14.2 DIGITAL CARD TEST
The digital card test requires that you connect 5 Vdc (24 Vdc maximum) to the DTB at the time the DTB
is installed.
The program runs a high/low test on each channel (0-7) for this card, utilizing both the
input and output sides of the channel.
INPUT STATE HIGH
INPUT STATE LOW
4
0
HGHILOW
| < VDC
HGTLOW
| <ovhe
Ng
L
INPUT
|L
SENSING
|
SVDC +
LNG
|
5 VIC +
CHO
MAO
CHO
MAG
ouTRUT
-
I
OUTPUT
T
I
o
LOW {0)
vie -
HIGH (1)
|
5 VOC -
C
}
DIAGNOSTIC TERMINAL BLOCK
Errored
DIGITAL 1K) ASSEMBLY
When the test begins, the program opens all channels in the instrument. With all of the channel outputs
on the card open (set to the low state), the 5 Vdc supply, sensed through the DTB pull-up resistor for each
channel, should set a high state on each channel input.
If the channel input is low, the problem could be either that the output will not go to a low state, or that
the input is incapable of sensing a high state.
If the first test passes, the program closes the channel output, and checks the channel input for a low
state. The input should be low because with the channel output closed, the bottom side of the DTB
pull-up resistor for that channel should be connected to the minus side of the 5 Vdc supply.
If the channel input tests high, the problem could be either that the output will not go to a high state, or
that the input is incapable of sensing a low state.
14-3
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