38
Manual – MOVIPRO® SDC with DeviceNet Interface
6
Process data exchange
DeviceNet Operating Characteristics
6.1.3
Bit-strobe I/O
Bit-strobe I/O messages are not contained in the SEW fieldbus profile. The messages
represent a DeviceNet-specific process data exchange. The master sends a broadcast
message that is 8 bytes (= 64 bits) long. One bit in this message is assigned to each
station in accordance with its address. The value of this bit may be "0" or "1", triggering
2 different responses in the recipient.
The following table shows an example of the data range of the bit-strobe request mes-
sage. This data range assigns the station address to the data bits.
Example: For example, the station with address (MAC-ID) 16 only processes bit 0 in
memory byte 2.
6.1.4
Timeout response with bit-strobe I/O
MOVIPRO
®
activates timeout monitoring. After a connection has been established, the
master must set the timeout interval.
The DeviceNet specification refers to an "expected packet rate" rather than a timeout
interval in this case. The expected packet rate is calculated on the basis of the timeout
interval using the following formula:
t
Timeout_Bit-Strobe_IO
= 4 x t
Expected_Packet_Rate_Bit-Strobe_IO
The expected packet rate is set using the connection object class 5, instance 3, attribute
9. The range of values runs from 0 ms to 65535 ms in 5 ms steps.
If the timeout time for the bit-strobe I/O messages has elapsed, this connection type
switches to timeout status. Incoming bit-strobe I/O messages are no longer accepted.
The timeout is not forwarded to MOVIPRO
®
.
The timeout status can be reset as follows:
• Via DeviceNet with the reset service of the connection object, class 0x05, instance
0x02, undetermined attribute,
• By interrupting the connection,
• Or via reset service of the identity object, class 0x01, instance 0x01, undetermined
attribute.
Bit value
Meaning
0
Sends back process input data only
1
Trigger fieldbus timeout response and send back process input data
Bit
7
6
5
4
3
2
1
0
Byte
0
ID 7
ID 6
ID 5
ID 4
ID 3
ID 3
ID 1
ID 0
1
ID 15
ID 14
ID 13
ID 12
ID 11
ID 10
ID 9
ID 8
2
ID 23
ID 22
ID 21
ID 20
ID 19
ID 18
ID 17
ID 16
3
ID 31
ID 30
ID 29
ID 28
ID 27
ID 26
ID 25
ID 24
4
ID 39
ID 38
ID 37
ID 36
ID 35
ID 34
ID 33
ID 32
5
ID 47
ID 46
ID 45
ID 44
ID 43
ID 42
ID 41
ID 40
6
ID 55
ID 54
ID 53
ID 52
ID 51
ID 50
ID 49
ID 48
7
ID 63
ID 62
ID 61
ID 60
ID 59
ID 58
ID 57
ID 56
