YOKOGAWA FA-M3 VITESSE F3CX04-0N, User Manual

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B1-6
IM 34M06H63-01E 2nd Edition : Jul.16,2015-00
B1.3 Writing and Reading After Powering On
Do not read and write to output data registers before module startup completes. This can
be ensured by checking that the MDLRDY relay is set.
Table B1.4 Relays Relating to Writing and Writing After Powering On
Input Relay Number
X

nn
*1
Symbol Description Data Values
X16 MDLRDY Module startup has completed
0: During startup,
1: Startup completed
*1:

denotes the slot number where the module is installed.
Figure B1.2 Checking for Module Startup Completion after Powering On
After powering on, it takes up to approximately 2 seconds for the module startup to
complete (startup initialization). Any data written during this period may be ignored. For
instance, if a write instruction to the special relay M35, “On for 1 Scan after Startup” is
used in a sequence program to start a program after powering on, the written data may be
ignored.
If data is written before the MDLRDY relay turns on, such data may be overwritten during
module initialization. If the write destination is a stored parameter, the data may be
overwritten by the stored data; if the write destination is a non-stored parameter, the data
may be overwritten by the default value.
Similarly, if data is read before the MDLRDY relay is set, the data read may be invalid.