Mitsubishi Electronics FX3G User Manual

FX

3S

/FX

3G

/FX

3GC

/FX

3U

/FX

3UC

 Series

Programming Manual - Basic & Applied Instruction Edition

6 What to Understand before Programming

The FX

3U

/FX

3UC

 PLC Ver. 3.00 or later can store symbolic information (data indicating the program configuration such

as structure and labels).
By using this function, you can read symbolic information from the PLC, and edit labels, function blocks, etc.
GX Works2 Ver. 1.62Q or later is required to store symbolic information.

→ Refer to the GX Works2 Version 1 Operating Manual (Common) for the details on symbolic information.

• When symbolic information is stored, it is deleted if the memory capacity set by parameters is changed.

After changing the memory capacity, write the symbolic information again.

• Memory cassettes (except for the FX

3U

-FLROM-1M) which save symbolic information are also supported 

by FX

3U

/FX

3UC

 PLCs whose version is earlier than Ver. 3.00. In that case, the FX

3U

/FX

3UC

 PLC operates, 

but the written symbolic information is invalid.

• For writing symbolic information and changing the set values of timers and counters using a peripheral 

device, it is recommended to create programs with set values specified indirectly.
If the set values are specified directly, programs cannot be restored from symbolic information after the set 
values are changed.

In GX Works2, program parts can be protected by setting the block password.
In the FX

3U

/FX

3UC

 PLC Ver. 3.00 or later, the setting "Read-protect the execution program" is available for the block

password.

→ Refer to the GX Works2 Version 1 Operating Manual (Common) for the details on the block password.

• In the PLC written by the computer using a project including a block password for which the setting "Read-

protect the execution program" is valid, restoration of programs is enabled only when the PLC stores the 
symbolic information.
For editing programs using a peripheral device which cannot read symbolic information (only supported by 
GX Works2 Ver. 1.62Q or later), do not use a block password for which the setting "Read-protect the 
execution program" is valid.

• When a peripheral device tries to read an execution program from the PLC that has been written to by a 

computer using a project including a block password for which the setting "Read-protect the execution 
program" is valid, a communication error occurs and reading is disabled.

• For writing a program using a peripheral device other than GX Works2 (Ver. 1.62Q or later) to a PLC that 

has been written to by a computer using a project including a block password for which the setting "Read-
protect the execution program" is valid, execute "Clear PLC memory" to clear programs before writing.
If a program is written without executing "Clear PLC memory" in advance, the written program cannot be 
read.

• It is not possible to write programs including the block password for which the setting "Read-protect the 

execution program" is valid to the FX

3U

/FX

3UC

 PLC whose version is earlier than 3.00.

• If a memory cassette which saves programs including a block password for which the setting "Read-

protect the execution program" is valid is used for the FX

3U

/FX

3UC

 PLC whose version is earlier than 3.00, 

the FX

3U

/FX

3UC

 PLC does not run normally.