Fast Data Exchange Plc-Nck - Siemens SINUMERIK 828D Function Manual

• Keyswitch and Emergency Stop signals
• Ready and status signals of the NCK
14.5.1.5

Fast data exchange PLC-NCK

DB4900
Data block DB4900 with a size of 1024 bytes is used for fast information exchange between the PLC and NCK.
The assignment of the area (structure) must be identically negotiated in the NC part program and PLC user user
program.
This data can be accessed from the NC part program using the commands $A_DBB[x], $A_DBW[x],
$A_DBD[x] and $A_DBR[x]; 0 ≤ x ≤ 1023 (see Parameter Manual, System variables).
In this case, the alignment of the data must be selected corresponding to its format, i.e. a Dword starts at a 4­byte
limit and a word at a 2­byte limit. Bytes can be located at any offset within the data field.
Data consistency is guaranteed for byte, word and Dword accesses. When transferring several data, the
consistency must be guaranteed on the user-side using semaphores, which can be used to detect the validity or
consistency of a block.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
P4: PLC for SINUMERIK 828D
14.5 Data interface
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