Configuring The Driver Blocks - Siemens Add 7 AddFEM Manual

Commissioning / Operation / Maintenance
5.5 Function Blocks for SIMATIC S7–400 for 6DL3100–8AA/–8AB
The AddFEM is "represented" by CFC function blocks (driver function blocks) in
the S7 CPU. The driver takes over the format conversion, data transportation and
monitoring of the AddFEM. The blocks can be used both for standard use (single
operation) as well as for all the provided redundancy configurations. The redun-
dancy operating modes are specified by the address configuration at the function
blocks and by the configuration in HW Config. The input and output values are
available at the block bars of the driver function blocks. In addition, parameters
such as the upper and lower measuring range limits have to be configured. A com-
plex of four individual driver function blocks are available for an AddFEM. The dri-
ver functions have been split so that...
–..the input and output bars of the blocks do not become too extensive and so that
the function blocks fit well onto a single function chart sheet of the CFC.
–..shorter signal run times can be implemented by separating input and output
blocks. To this purpose the processing sequence Input, Processing, Output has to
be observed within the respective watchdog interrupt level.
5.5.1

Configuring the Driver Blocks

Despite the block subdivision, organizational information, such as the subnet ID
(PROFIBUS DP line number) and rack number (PROFIBUS DP slave address)
etc., have to be configured at a single driver function block, the FEM_AI. The inter-
nal communication of the drivers for the PROFIBUS DP is carried out for all the
input and output data block–by–block, runtime–optimized and consistently. When
configuring the driver function blocks the parameters BLOCKCON, BLOCKCNI
and BLOCKCNO have to be used to create the internal connection between the
function blocks.
The parameters BLOCKCON, BLOCKCNI and BLOCKCNO are of the data type
STRUCT. The structure has a word–by–word structure and contains all the infor-
mation relevant for the driver function blocks.
The parameter BLOCKCON is "passed on" by the individual blocks. Starting from
the FEM_AI block the parameter is interconnected to the BLOCKCNI input of the
FEM_DI block. The BLOCKCNO output is interconnected to the BLOCKCNI input
of the FEM_DO block. Its BLOCKCNO output is interconnected to the
BLOCKCON input of the FEM_AO block.
In order to ensure consistent input and output data in a cycle, the blocks have to
be installed in a watchdog–interrupt cycle in the following order:
1) FEM_AI
2) FEM_DI
3) FEM_DO
4) FEM_AO
5-34
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