migra MPB PB
Large Format, Graphics Compatible Display with Profibus Interface
Page 39
microSYST Systemelectronic GmbH, Am Gewerbepark 11, 92670 Windischeschenbach
+49 9681 91960-0,
+49 9681 91960-10, [email protected], www.microsyst.de
3.11.4 DP Output Data
The user must enter MIGRA control frames into the DP output data:
DP Output
Byte 1
Byte 2
Byte 3
Byte 4
...
Byte n + 2
Toggle byte Length
byte = n
Frame byte 1
Frame byte 2
...
Frame byte n
In order to transmit a frame to the MIGRA, the individual frame bytes must be
entered at the Profibus side as output bytes 3 through (n + 2). After the length
byte (= frame length n) has been entered, the toggle byte must be changed in
order to start transmission.
Before the next frame can be transmitted, the MIGRA must get enough time
for executing the current command!
For this, it is strongly recommended to wait for the MIGRA response frame
(see chapter “DP Input Data”).
Alternatively, a minimum waiting time has to be ensured. It depends on the
type and content of the respective control frame and must be determined ex-
perimentally (if the the waiting time is too short, the new message will be ig-
nored
). Thereby, there must be added a “security buffer” of about 30%, be-
cause the execution times for commands may vary within a certain range (de-
pending on firmware version)!
3.11.5 DP Input Data
MIGRA response frames are notified to the user in the DP input data:
DP Input
Byte 1
Byte 2
Byte 3
Byte 4
...
Byte n + 2
Toggle byte Length
byte = n
Frame byte 1
Frame byte 2
...
Frame byte n
Each time a response frame has been received from the MIGRA, it is entered
as input bytes 3 through (n + 2), and the frame length (n) is entered as input
byte 2 (= length byte). The toggle byte is finally increased by 1.