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Series 18C/19C/25C Temperature/Process Controller
RS-485
Communications
Options B&C: RS-485
(one-to-many) Communications
Option Description: Provides one-to-
many communications.
Terminate the controller furthest from the
computer by either connecting a 120-ohm,
1/4-watt resistor between terminals 23
and 24.*
*Terminate only if the total distance from con-
troller to computer exceeds 2000 ft. Termination
is to minimize signal reflections or "echoes" on
the line.
Transducer
Excitation
Options 1, 2, 3, and 4:
Transducer Excitation
Option Description: The transducer
excitation option provides power to remote
transducers. The transducer outputs, in
turn, provide a signal to the controller
input which can be scaled in the
appropriate engineering units.
All options will provide at least 20 mA. The
transducer circuitry is thermally protected
from short circuits.
13
3
14
4
15
5
6
16
17
7
8
18
19
9
21
22
1
2
0
0
SENSOR
INPUT
–
–
MA
MV
T/C
RTD
V
+
+
NOTE: FOR 2 WIRE RTD
JUMPER 18 & 20
6
SIG GND
RCV
XMT
SIG GND
B(-)
A(+)
B(-)
A(+)
1
1
1
23
24
2
12
13
3
14
4
Option 1: 10 Vdc
Option 2: 12 Vdc
Option 3: 15 Vdc
Option 4:
5 Vdc
0 to1 volt out = 0 to100% RH
(6 to 30 Vdc input)
Relative Humidity Sensor
RS 232
RS 485
SIG GND
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