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FX2N-32DP-IF Profibus-DP Interface Unit
7.2.1
Exchanged Data by Default User Parameter
After power on, the bus node does not know about the I/O features of the connected special
function blocks. So each special function block is assigned to one reading command and one
writing command. The exchanged data is as follows:
Table 7.6: Exchanged Data
Data
word
Special function block's BFM address is
1st
written for input data (Reading from 32DP-IF)
(Bit15 = write flag)
This data is written to special function block's
2nd
BFM for output data.
Special function block's BFM address is
3rd
written for output data (writing to 32DP-IF)
(Bit15 = write flag)
Example
Reading BFM #17 and writing K1000 to BFM #9 in the special function block.
Table 7.7: Example Exchanged Data
Data
word
8011hex = 11hex (17 dez = BFM #17) + 8000 hex
1st
(bit15=1)
2nd
03E8 hex = (1000 dez)
8009 hex = 09 hex (9 dez = BFM #9) + 8000 hex
3rd
(bit15=1)
Basically this parameter block is only for the case when reaching the limits of the parameter
data memory or Profibus I/O data memory. It is possible to use this block for every special
function block listed above, but it is more comfortable to use the extended or short parameter
settings of a special function block. The high address BFM area of some Special Function
Block's (Ex- FX
Communication procedure:
For further explanation, the first word of the cyclical send data is called the "FROM
ADDRESS", the second word is called the "TO DATA" and the third "TO ADDRESS".
According to this "FROM DATA", "TO DATA (read back)" and "TO ADDRESS (read back)"
describes the first, second and third word of the cyclically received data. The most
significant bit (MSB) of the "FROM ADDRESS" and the "TO ADDRESS" is a flag which is
used to request a FROM/TO instruction inside the FX
of the "FROM ADDRESS" and the "TO ADDRESS" are transmitted to the FX
no read/write command is executed. If the MSB is set to 1, the BFM specified by bit 0 - 14 is
addressed.
Example- if the "TO ADDRESS" is 8000 Hex, the content of "TO DATA" is written to BFM 0.
Output area (send)
Output Data
-232IF) is only accessible by using this communication format.
2N
Input area (receive)
This value is BFM's data read from special
function block.
This value was written to special function
block's BFM.
(Written value is read back)
This value was special function block's BFM
address.
(Written value is read back)
Input Data
nnnn = hex value of BFM #17
03E8 hex = hex value of BFM #9
8009 hex = verification of BFM address
-32DP-IF. If this bit is 0, the contents
2N
User Parameter 7
-32DP-IF but
2N
7-9
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