Yaskawa 120 Series I/O Modules - Manual (Page 287)

7 Maintenance
7.2.1 Hot Swapping
7-8
Note: (1) Do not hot swap more than one Module at a time, even if the Modules all sup-
port hot swapping. Hot swapping more than one Module at the same time may
cause the CPU to reset or to stop completely.
(2) When hot swapping on an I/O Module which supply DC power as the I/O power
supply, there is no need to setup safety switches. However, it may cause I/O
signal chatter when inserting or removing a terminal block or a connector to or
from the Module. If this is a problem, then setup a chatter prevention switch for
each Module and be sure to turn this switch OFF to turn OFF the DC power
supply.
(3) When hot swapping, never short-circuit the terminal block or the connectors of
the Module.
(4) Inserting or removing a Module which does not permit hot swapping may cause
the CPU Module to stop.