ROC364 Instruction Manual
3-13
Input and Output Modules
Rev Jun/05
3.4.9 Discrete Output Relay Module
A schematic representation of the field wiring connections to the output circuit of the Discrete Output
Relay module displays in Figure 3-15.
NOTE:
The Discrete Output Relay module is designed to operate only with discrete devices
having their own power source. The module will be inoperative with non-powered devices.
The Discrete Output Relay module operates by providing both normally-closed and normally-open
contacts to a field device. Normally-closed contacts use terminals B and C, and normally-open contacts
use terminals A and B. ROCLINK configuration software controls the status of the contacts (open or
closed).
There are two versions of the DO Relay module. The 12 volts version (which has a 12 volts energizing
coil) must be used when the ROC input voltage is a nominal 12 volts dc, and the 24 volts version (which
has a 24 volts energizing coil) must be used when the ROC input voltage is a nominal 24 volts dc.
TERMINAL A CONNECTION TO BE MADE FOR NORMALLY OPEN APPLICATIONS
TERMINAL B IS COMMON
TERMINAL C CONNECTION TO BE MADE FOR NORMALLY CLOSED APPLICATIONS
V
O
= VOLTAGE FROM DISCRETE DEVICE = 0 TO 30 VDC OR 0 TO 115 VAC, 5 A MAX
DO RLY
V
S
DOC0147A
CONTROL
COM
NC
NO
C
B
A
DISCRETE DEVICE
SELF-POWERED
–
+
V
O
Figure 3-15. Discrete Output Relay Module Field Wiring
3.4.10 Pulse Input Source Module
A schematic representation of the field wiring connections to the input circuit of the Pulse Input
Source module is shown in Figure 3-16.
The Pulse Input Source module is designed to operate only with non-powered discrete devices,
such as “dry” relay contacts or isolated solid-state switches. Use of the module with powered
devices may cause improper operation or damage to occur.
The Pulse Input Source module provides a voltage across terminals B and C that is derived from internal
voltage source V
s
. When a field device, such as a set of relay contacts, is connected across terminals B
and C, the opening and closing of the contacts causes current to either flow or not flow between V
s
and
ground at terminal C.
This interrupted, or pulsed current flow is counted and accumulated by the PI Source module, which
provides the accumulated count to the ROC electronics upon request.
