NORD Drivesystems BU0220 - Manual (Page 91)

8 Additional information
BU 0220 GB-0912 Subject to technical amendments 91
Reading parameters
Within the DPM2 master program, the system module SFB52 "RDREC" (read record) is used to read
parameters. This system module reads the data set of the addressed component (module) of a DP slave. This
may be a central module or a decentralised component (PROFIBUS DP), a technology unit. If an error occurs
during data transfer, this is indicated via an output parameter (ERROR and STATUS) of the system module.
Several settings must be noted for the use of this system module.
If for example a DP-V1 slave is planned via GSD (Rev. 3 or later), the DP master must be set to "DPV1".
Otherwise (example setting "S7 compatible") no data sets may be read with SFB 52 from the I/O modules in
the application program, as the DP master would be addressed to the wrong slot (planned slot +3).
The SFB 52 "RDREC" is an asynchronous SFB, i.e. processing extends over several SFB call-ups.
Sequence
To read the parameter of the frequency inverter, the PROFIBUS DP master first sends a WRITE control
command to the relevant DP slave (PROFIBUS DP technology unit), which confirms the query. A READ
command triggers the transfer of the parameter data to the control unit.
The issue of a read command (SFB 52) without a previous write command (SFB 53), results in an error
message (E009) by the relevant frequency inverter.
Writing parameters
Within the DPM2 master program, the system module SFB52 "WRREC" (write record) is used to write
parameters. This system module writes (transfers) the data set of the addressed component (module) of a DP
slave. Several interface settings in the DP master interface must be noted to ensure correct operation.
The SFB 53 "WRREC" is an asynchronous SFB, i.e. processing extends over several SFB call-ups.
Sequence
To change the parameter of the frequency inverter, the PROFIBUS DP master first sends a WRITE control
command to the relevant DP slave (PROFIBUS DP technology unit), which confirms the query. If necessary,
the transferred parameter changes can be checked by means of a READ command.