06/0528
8.6.3 Handling of the data sets / cyclic writing
Access to the parameter values is done on the basis of the parameter number and the
required data set. Parameters, the values of which exist once (data set 0), and also
parameters, the value of which exist four times (data set 1...4), exist. The latter are
used for the data record change-over of a parameter.
If parameters existing four times in the data sets are described with the specification
data set = 0, all four data sets are set to the same transmitted value. A reading
access with data set = 0 to such parameters is only successful if all four data sets are
on the same value. If this is not the case, error 9 = "Values of the data sets differ" is
reported.
Caution! The values are entered into the EEPROM automatically on the controller.
If values are to be written cyclically with a high repeat rate, there must be
no entry into the EEPROM, as it only has a limited number of admissible
writin
g cycles (about 1 million cycles). If the number of admissible writing
cycles is exceeded, the EEPROM is destroyed.
To avoid this, cyclically written data can be entered in the RAM without a writing cycle
taking place on the EEPROM. The data are then not stored safe against zero voltage
and have to be rewritten after a power off/on.
This mechanism is activated by the tar
get data set being increased by five in the
specification of the data set.
Writing onto a virtual data set in the RAM
Parameter EEPROM RAM
Data set 0 0 5
Data set 1 1 6
Data set 2 2 7
Data set 3 3 8
Data set 4 4 9
8.6.4 Subindex 01, int/uint parameters
The int/uint parameters have a length of 2 bytes. The distinction between int and uint
is specified via the internal parameter tables. A data type is firmly assigned to each
parameter. Evaluation corresponding to the sign in front is done product-internally on
the basis of the data type in question.
Subindex 01 has a data length of 6 bytes.
Subindex 01
Byte 0 1 2 3 4 5
low high low high
Contents
Parameter number +
data set x 1000
SEL
ENQ
ACK
NAK
00
Parameter figure