Mitsubishi MELSEC-WS series, Руководство пользователя

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Chapter 7
74
Electrical installation
 Avoid ground loops between the GND of the RS-232 interface and the connection
A2 of the CPU module, e.g. by using optocouplers.
 Depending on the external loads, especially for inductive loads, additional
external protective elements, e.g. varistors or RC elements may be necessary in
order to protect the outputs. For operating limits see Chapter 12. Take into
account that the response times may increase, depending on the type of
protective element.
 If a module is replaced the correct terminal assignment has to be guaranteed, for
example by labelling or suitable cable routing.
 If standing behind the protective devices (e.g. safety light curtain) is possible,
mount the reset button so that it cannot be actuated by a person located in the
hazardous area. When operating the control device of the reset button, the
operator must have full visual command of the hazardous area.
 Between the supply circuit and output circuit, and between the input circuit and
output circuit in the WS0-4RO module are isolated. On the other hand, those in
the safety I/O module are not isolated.
Limited short-circuit recognition!
An WS0-XTDI has two test signal generators. One test signal generator is
responsible for the odd-numbered test outputs X1, X3, X5 and X7, the other for the
even-numbered test outputs X2, X4, X6 and X8.
Short-circuits between test signal generators on MELSEC-WS I/O modules are
detected, also between test signal generators on different modules, provided the test
gaps are
≤ 4 ms and the test periods are ≥ 200 ms for the relevant test outputs.
Short circuits to 24 V DC (stuck at high) at inputs connected to test outputs are
detected independently of the test gap time.
Please be aware that at the WS0-XTDI the odd-numbered test outputs X1, X3, X5
and X7 are connected to one common test signal generator and that the even-
numbered test outputs X2, X4, X6 and X8 are connected to another common test
signal generator. Therefore short circuits between test outputs X1, X3, X5 and X7
cannot be detected. The same applies respectively for test outputs X2, X4, X6 and
X8.
Take this into consideration during the wiring (e.g. separate routing, sheathed
cables)!
Reverse current at WS0-XTIO / WS0-XTDI inputs in case of ground interruption
In case of an internal or external ground interruption there can be a reverse current
from the power supply of the CPU module (memory plug terminal A2) to the safe
inputs I1…I8 of WS0-XTIO / WS0-XTDI modules. This must be considered if other
inputs are connected in parallel to these inputs, so that this reverse current does not
lead to an unintended High level at the parallel connected inputs.
ATTENTION