Siemens FM 458-1 DP - S7 RD, S7 RD_B, S7 RD_I, S7 RD_D Read from the Peripheral Area of the S7-CPU

Communication blocks
Function Blocks - FM 458-1 DP 2-25
Edition 12.2004
2.3.6 S7RD, S7RD_B, S7RD_I, S7RD_D Read from the peripheral area of the
S7-CPU
S7RD
Offset
―
I OFF Y R
―
Output
Enable
―
BO EN QF BO
―
error output
The function blocks, read from the peripheral area of the S7-CPU, can
only run with an FM 458 application module.
The S7RD, S7RD_B, S7RD_I, S7RD_D blocks only differ by the data
type at the output, which must correspond with the parameters to be
read:
• S7RD: REAL
• S7RD_B: BOOL
• S7RD_I: INT
• S7RD_D: DINT
With this block, data can be read into the assigned net data area of the
SIMATIC S7-CPU, (periphery output) assigned to the FM 458 application
module. This PE area is 128 bytes.
If the enable signal is set, the appropriate value is read from the PA area
and made available at output Y.
The offset determines at which location in the PA area, the value is
retrieved.
Depending on the block- or data type, the offset is specified as follows:
• for REAL data type in 4-byte steps (data length)
value range of the offset: 0 . . . 31
• for BOOL data type in 1-byte steps (data length).
value range of the offset: 0 . . . 127
• for INT data type in 2-byte steps (data length).
value range of the offset: 0 . . . 63
• for DINT data type in 4-byte steps (data length).
value range of the offset: 0 . . . 31
Output QF has the value 1, if an invalid offset was selected, or the block
is not configured on the FM 458.
Symbol
Brief description
Mode of operation