migra MPB CAN
Large Format Graphics Compatible LED Display with CANopen Interface
Page 48
microSYST Systemelectronic GmbH, Am Gewerbepark 11, 92670 Windischeschenbach
+49 9681 91960-0,
+49 9681 91960-10, [email protected], www.microsyst.de
Example: Transmitting an RS Frame
(transmit RS frame: “ABCDEFG12345”)
1. Break down the RS frame to be transmitted into sub-frames of max. 7 bytes each.
* 1
st
sub-frame (7 bytes) = 41
h
42
h
43
h
44
h
45
h
46
h
47
h
* 2
nd
sub-frame (5 bytes) = 31
h
32
h
33
h
34
h
35
h
2. Transfer the sub-frames to the interface.
* Transmit PDO: 17
h
41
h
42
h
43
h
44
h
45
h
46
h
47
h
(prerequisite: last toggle bit status = 0)
* Wait until the PDO has been transmitted.
* Wait an additional 5 ms (to allow the interface enough time to evaluate the
PDO).
* Transmit PDO: 85
h
31
h
32
h
33
h
34
h
35
h
XX
h
XX
h
* Wait until the PDO has been transmitted.
* Wait an additional 5 ms (to allow the interface enough time to evaluate the
PDO).
3. Wait until the RS frame has been transmitted:
*
Example 19,200 baud, 8 data bits, even parity, 1 stop bit
=> Transmission time = 1.3 x 12 x (11 x 1/19,200) s = 9 ms
=> Wait at least an additional 9 ms (the function byte is
not
evaluated within this time period!)
*
Query the “end bit” via SDO:
*
Transmit CAN frame (COB ID = 600
h
+ node ID):
40
h
00
h
20
h
01
h
00
h
00
h
00
h
00
h
*
Receive CAN frame (COB ID = 580
h
+ node ID):
4F
h
00
h
20
h
01
h
“function byte” 00
h
00
h
00
h
As soon as bit 7 (end bit) of the “function byte” is changed to 0, the next RS
frame can be transferred to the interface.