6
DIAGNOSTICS
6.1 Preliminary checks
Check whether the input wiring and/or expansion cables are properly connected on FX-4AD analog
special function block.
Check that the FX system configuration rules have not been broken, i.e. the number of blocks does
not exceed 8 and the total system I/O is equal or less than 256 I/O.
Ensure that the correct operating range has been selected for the application.
Check that the MODE switch on the FX-4AD panel is set to the READY position.
Check that there is no power overload on either the 5V or 24V power source, remember the loading
on a FX base unit or a powered extension unit varies according the number of extension block or
special function blocks connected.
Put the FX base unit into RUN.
6.2 Error checking
If the FX-4AD special function block does not seem to operate normally, check the following items.
●
Check the status of the POWER LED.
Lit : The extension cable is properly connected.
Otherwise: Check the connection of the extension cable.
●
Check the external wiring.
●
Check the status of "24V" LED (top right cover of the FX-4AD).
Lit: FX-4AD is OK, 24V DC power source is OK.
Otherwise: Possible 24V DC power failure, if OK then possible FX-4AD failure.
●
Check the status of the "A/D" LED (top right cover of the FX-4AD)
Lit: A/D conversion is proceeding normally
Otherwise: Check buffer memory #29 (error status). If any bits (b2 and b3) are ON, then this is why
the A/D LED is OFF.
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