Siemens QUADLOG - Unterminated I;O Cable Assembly Connections; Unterminated I;O Cable Assembly

SDQLCAI-1 Installation
May 2002 2-19
2.7.3 Unterminated I/O Cable Assembly Connections
Connect field devices to user-supplied termination hardware (e.g. terminal blocks). Table 2–2 lists the
wire color and identification information needed for I/O wiring termination. Refer to your system’s
wiring diagrams as necessary.
When an unterminated I/O cable assembly is used, it is recommended that you to manually wire the I/O
Supply Monitor (sense) line for the I/O power supply. The CAI module connected to this cable uses this
line to verify the presence and magnitude of the 24 Vdc source. When the CAI module is in service and a
power supply voltage anomaly is sensed, an error (SSC 57: EC 16 - I/O Power Supply Lost) is reported.
Connections are detailed in Figure 2–9 for both redundant and non-redundant power supplies. As shown,
a customer-supplied 5 K (¼ watt) resistor is to be installed between the 24 Vdc source and the cable.
When redundant I/O power supplies are used, make sure this connection is made after the power supply
isolation diodes (which are typically of type 1N4001).
NOTE
The I/O source diagnostic test is not performed until the I/O power
supply is connected to the I/O Supply Monitor line and the voltage level
is within tolerance. If the line is left unconnected, no response is taken
by the controller for a failed power supply, other than the channel errors
reported due to the loss of I/O power.
Interconnect I/O Cable
+
-
Power
Supply
24 V
24 Vdc
Single Power Supply
COM
5K
Unterminated
To Module
I/O Supply Monitor Line
(Blue/Violet Wire Color)
Common
(Wire Color Varies)
Terminal
Strip
Interconnect I/O Cable
+
-
Power
Supply
24 V
24 Vdc
Redundant Power Supplies
COM
Unterminated
To Module
I/O Supply Monitor Line
(Blue/Violet Wire Color)
Common
(Wire Color Varies)
Terminal
Strip
+
-
Power
Supply
24 Vdc
Terminal
Strip
A
B
To CH+
To CH+
Isolation
Diodes
5K
Figure 2–9 I/O Supply Monitor Line Connections