Manual – MOVIDRIVE® MDX61B MOVI-PLC® DHP11B Control Card
41
5
Parameter setting via PROFIBUS-DP
PROFIBUS-DP Operating Characteristics
Writing a
parameter with
PROFIBUS-DP
(Write)
Due to the cyclical transfer of the parameter channel, to execute a
write
service via the
8 byte MOVILINK
®
parameter channel, the handshake bit may only be changed if the
complete parameter channel has been set up for the specific service. Observe the fol-
lowing sequence when writing a parameter:
1. Enter the index of the parameter to be written in byte 2 (Index high) and byte 3 (Index
low).
2. Enter the data to be written in bytes 4...7.
3. Enter the service identifier and the data length for the
write
service in the manage-
ment byte (byte 0).
4. Transfer the
write
service to the DHP11B control card by changing the handshake
bit.
The DHP11B control card now processes the
write
service and sends the service con-
firmation back by changing the handshake bit.
The following table shows how a
write
service is coded in management byte 0. The data
length for all parameters in the DHP11B control card is four bytes. This service is now
transferred to the DHP11B control card when the handshake bit changes.
Consequently, a
write
service on the DHP11B control card always has the management
byte coding 32hex or 72hex.
Parameter set-
ting sequence
with
PROFIBUS-DP
Taking the example of the
write
service, the following figure shows the parameter setting
sequence between the higher-level controller and the DHP11B control card via
PROFIBUS-DP. To simplify the sequence, the following figure only shows the manage-
ment byte of the parameter channel.
The parameter channel is only received and returned by the DHP11B control card while
the higher-level controller is preparing the parameter channel for the
write
service. The
service is not activated until the moment when the handshake bit is changed (in this
example, when it changes from 0 to 1). The DHP11B control card now interprets the
parameter channel and processes the
write
service. However, it continues to respond
to all telegrams with handshake bit = 0.
The executed service is acknowledged with a change of the handshake bit in the
response telegram of the DHP11B control card. The higher-level controller now detects
that the received handshake bit is the same as the one that was sent. It can now prepare
another parameter setting procedure.
7 / MSB
6
5
4
3
2
1
0 / LSB
0
0/1
1)
1) Bit value is changed
1
1
0
0
1
0
Service identifier
0010 = Write parameter
Data length
11 = 4 bytes
Handshake bit
Must be changed on every new job in cyclical transmission.
Status bit
0 = No fault in service execution
1 = Fault in service execution
0
0
I
