I/O Terminal /
MANUAL CONFIGURATION
39
Dummy Output Byte
The Bus Coupler's PROFIBUS DP ASIC can only generate an interrupt after reception of a
Data_Exchange telegram if output data has been received. This means that at least one
output byte must be transferred via DP in synchronous mode. If only input terminals are
plugged in, and no output data is therefore present, a dummy output byte can be configured.
It is activated in the UserPrmData, and must be entered as the module in the CfgData. The
extended GSE file for the Bus Coupler is, however, necessary for this:
Byte
Bit
Value
Description
3
5
1
bin
Dummy output byte activated
It is also necessary for the dummy output byte to be configured in the CfgData before the
complex terminals:
CfgData
DP Modules
0x20
Dummy output byte
Standard-Bus Cycle Counter
In order for the master to be able to check reliably whether precisely one (or two) Standard-
Bus cycles are always being carried out during one DP cycle, a Standard-Bus cycle counter
can be transferred in the input data from the Bus Coupler to the master. This is incremented
after each Standard-Bus cycle (0 is omitted , so that 1 follows after 255). The Standard-Bus
cycle counter must be activated in the UserPrmData and entered as a module in the CfgData.
The extended GSE file for the Bus Coupler is, however, necessary for this:
Byte
Bit
Value
Description
3
3
1
bin
Standard-Bus cycle counter activated
It is also necessary for the Standard-Bus cycle counter byte to be configured in the CfgData
before the complex terminals:
CfgData
DP Modules
0x10
Standard-Bus cycle counter
6.4
DPV1 – Acyclic Data Transfer
This section explains acyclic data transfers.
6.4.1 DPV1
Interface
By default, one MSAC_C1 connection and one MSAC_C2 connection with 52 bytes of data
(4 bytes DPV1 header plus 48 bytes of user data) are supported. The MSAC_C1 connection
is established along with cyclic connection, and can be activated via the UserPrmData:
