Instruction Manual

B. Supplementary information
B−97
Festo P.BE−GDCP−SFC−LACI−PB−EN en 0812NH
B.4.5 Checking the data
Permitted value ranges Transferred parameters and values are checked by the
SFC−LACI before being accepted.
Note
In the case of invalid parameters or values, an error
message will not appear in the response; rather, the
received value will always be returned (Echo).
Recommendation:
Check that values have been written correctly by
downloading the current contents of the object with a
subsequent Read command. The higher level controller must
compare the
sent command with the Echo" from the
SFC−LACI and check the checksum.
Note
The following applies when writing the objects:
 Discrete values (values from a value list):
an invalid value will not be accepted; the previously
valid value will be retained.
 Continuous values (e.g. lengths, speeds, etc.): an imper
missible value will be limited to the nearest permitted
value.
Error messages If there are errors in the
commands (e.g. syntax errors,
transmission errors), the value <0x00FF> will be transmitted
(object 2FF0h) instead of the usual reply. Possible causes:
 incorrect initial character, separating character or empty
character
 incorrect hex digit
 incorrect value type.