Teledyne GFC-7000E - Trace CO2 Analyzer - Manual (Page 126)

Model GFC7000E Instruction Manual Operating Instructions
04584 Rev A1 115
6.13. Remote Operation of the Analyzer
6.13.1. Remote Operation Using the External Digital I/O
6.13.1.1. Status Outputs
The status outputs report analyzer conditions via optically isolated NPN transistors, which sink up
to 50 mA of DC current. These outputs can be used interface with devices that accept logic-level
digital inputs, such as programmable logic controllers (PLC’s). Each Status bit is an open collector
output that can withstand up to 40 VDC. All of the emitters of these transistors are tied together
and available at D.
NOTE
Most PLC’s have internal provisions for limiting the current that the input will draw from
an external device. When connecting to a unit that does not have this feature, an
external dropping resistor must be used to limit the current through the transistor
output to less than 50 mA. At 50 mA, the transistor will drop approximately 1.2V from
its collector to emitter.
The status outputs are accessed via a 12-pin connector on the analyzer’s rear panel labeled
STATUS. The function of each pin is defined in Table 6–24.
C
o
n
n
e
c
t to
Int
er
n
a
l G
ro
und
of
Mo
ni
tor
ing
D
e
vi
c
e
STATUS
1 2 3 4 5 6 7 8 D +
SY
ST
E
M
O
K
H
IG
H
RA
NG
E
CON
C
V
A
LI
D
Z
E
R
O
CAL
SP
A
N
CAL
DIAG
NO
S
T
IC
MODE
AL
ARM 1
AL
ARM 2
Figure 6-10: Status Output Connector