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Wiring Information
You should protect the field power supply of the Safety digital output modules by a
fuse. This fuse protects the module not only against reversed field power supply, but
also against field power supply overvoltage. There must not be any current
limitation, and the field power supply must be able to deliver 50 A during 0.2 s in case
of short circuit. The fuse must be chosen according to the driven load and must not
exceed 16 * 0.5 * 1.25 = 10 A fast-blow (IEC 61131-2). Thus, you should use a fast
10 A fuse on the field power supply input of each digital output module.
WARNING
SHORT-CIRCUIT RISK
Use a 10 A, 250 V fast-blow fuse to protect the field power supply against reversed
power and over-voltage.
Failure to follow these instructions can result in death, serious injury, or
equipment damage.
The ground of the field power supply must be wired to the terminal block of the
output module separately from the ground of the actuators. For further details, see
the Quantum with Unity Pro Discrete and Analog I/O Reference Manual.
NOTE: It is recommended connecting at least 2 ground lines (common 0V) to the
terminal block.
Description of the Diagnostics
To check if both switches can open and close, a pulse test is performed on the
output modules (in the module’s internal circuitry, diagnostic cycles are inserted
periodically). The diagnostic sequence is as follows:
Stage
Description
1
The switch command is modified for a time short enough to not affect actuators,
which is a maximum of 1 ms. If the actuator is sensitive to this 1 ms, using 2
outputs of the same output module in parallel can avoid a disturbance.
2
The result is verified and the correct switch command is restored.
Description of the Power Supply Supervision
Each output circuit is composed of 2 switches in series, controlled separately by the
2 processors. The first micro processor uses a DOD to drive its switch, whereas the
second one drives its switch after de-serialization. In both micro processor systems,
the midpoint voltage is compared to 1 threshold. Both systems exchange their
results, evaluate the midpoint state, and diagnose the status of the switches at each
cycle. If a fault in 1 of the channels is detected, it is shut down, which is signaled to
the CPU by setting a diagnostic bit.
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33003879 01/2010
This document provided by Barr-Thorp Electric Co., Inc. 800-473-9123
www.barr-thorp.com