MOVIDRIVE
®
PROFIBUS DFP11A
27
The PROFIBUS-DP
Interface
3
3.7.1.1 Management of the Parameter Channel
The entire parameter adjustment procedure is co-ordinated using byte 0: Management. This byte
makes important parameters, such as Service Identifier, data length, version and status, of the exe-
cuted service available. Fig. 25 shows that bits 0, 1, 2 and 3 contain the service identifier, in other
words, they define which service is to be executed. Bit 4 and bit 5 contain the data length in bytes
for the Write service, which in the case of SEW drive inverters should normally be set to 4 bytes.
01229AEN
Fig. 25: Structure of the management byte
Bit 6 is used as a handshake between the control system and the drive inverter. It initiates the exe-
cution of the transferred service in the drive inverter. As the parameter channel is transferred in
each cycle with the process data, particularly with PROFIBUS-DP, execution of the service in the
drive inverter must be initiated by signal transition using the handshake bit 6. The value of this bit
is therefore toggled each time a new service is to be executed. The drive inverter uses the hand-
shake bit to signal whether the service has been executed or not. The service is executed when the
handshake bit received by the control system corresponds to the handshake bit sent. Status bit 7
indicates whether the service was executed properly or produced a fault.
3.7.1.2 Index Addressing
Byte 2: Index High and byte 3: Index Low are used to identify the parameter to be read or written
via the fieldbus system. The parameters of a drive inverter are addressed using a standard index,
irrespective of the type of fieldbus system. Byte 1 should be considered reserved and must gener-
ally be set at 0x00.
7
6
5
4
3
2
1
0
MSB
LSB
Bit:
Byte 0: Management
Service identifier
0000 = No Service
0001 = Read Parameter
0010 = Write Parameter
0011 = Write Parameter volatile
0100 = Read Minimum
0101 = Read Maximum
0110 = Read Default
0111 = Read Scale
1000 = Read Attribute
Data length:
00 = 1 byte
01 = 2 bytes
10 = 3 bytes
11 = 4 bytes (must be set)
Handshake bit
must be toggled
for each new service
Status bit
0 = correct execution of service
1 = faulty execution of service