Lenze E94AxPExxxx - Manual (Page 73)

Lenze · 9400 Servo PLC· Reference manual · DMS 4.0 EN · 11/2013 · TD05/06
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4 PLC functionality
4.8 Appendix
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4.8.5 Data consistency
The data consistency of the system variables in the control configuration as well as of the PDO
network variables is ensured for the user task with the highest priority. If these data have to be used
in tasks with a lower priority as well, the user must provide appropriate consistency mechanisms.
Due to the fact that the »9400 ServoPLC« is based on a 32-bit architecture, all accesses up to this
width are atomic accesses. One exception are the single bit accesses which can only be
implemented as Read-Modify-Write and are not provided with a protection against interruption by
another task.
Accesses with a width of 64 bits are atomic as well since the load and save command in the
processor architecture for two related values is handled atomically.
4.8.6 Storage capacities and memory modules
RAM memory
In the RAM memory, the user data is limited to the following size:
Retain memory
The values of the retain variables are permanently saved in the retain memory. In this way, they are
even after mains disconnection available to the program. An explicit saving of the parameter set is
not required.
• Retain variables are declared by means of the variable class VAR RETAIN.
• Retain variables are used as a memory which can be symbolically addressed.
• With every program download, the retain variables are reset to their initialisation value. If no
initialisation value is defined, the corresponding retain variable is initialised with the value "0".
• In the online mode of the »PLC-Designer« you can reset the retain variables in the controller to
their initialisation value using the commands Online  Reset (cold) or Online  Reset (original).
• The available retain memory depends on the memory module plugged into the controller:
• Memory module MM340: 4992 bytes
• Memory module MM440: 64 kbytes
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Note!
With controllers of the Servo Drives 9400 series, the program code is executed in the
RAM memory.
The device command C00002 = "11: Save start parameter" serves to protect the
parameter settings against data loss against e.g. mains failure. This command serves to
archive the data safe against mains failure in the memory module.
Memory for Size
Program code 512 kByte
Data 256 kByte
User parameter 196 kByte
Cam data 512 kByte