Manual – MOVIPRO® SDC with DeviceNet Interface
37
6
Process data exchange
DeviceNet Operating Characteristics
6
DeviceNet Operating Characteristics
6.1
Process data exchange
6.1.1
Polled I/O
The polled I/O messages correspond to the process data telegrams to MOVIPRO
®
. Up
to 64 process data words can be exchanged between the controller and MOVIPRO
®
in
this case. The process data length is set, for example, using the
MC_DeviceNetPDConfig
function block.
6.1.2
Timeout response with polled 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_inverter
= t
Timeout_interval_polled_IO
= 4 x t
Expected_packet_rate_polled_IO
The expected packet rate is set using the connection object class 5, instance 2, attribute
9. The range of values runs from 0 ms to 65535 ms in 5 ms steps.
The expected packet rate for the polled I/O connection is converted into the timeout in-
terval and displayed in the device as timeout interval in index 8606 in the bus diagnostics
in the parameter tree.
This timeout interval is retained in the device whenever the polled I/O connection is
dropped, and the device switches to timeout status after the timeout interval has
elapsed.
The timeout interval must not be altered using the PLC Editor or the IEC program be-
cause it can only be activated via the bus.
If the timeout time for the polled I/O messages has elapsed, this connection type
switches to timeout status. Incoming polled I/O messages are no longer accepted.
The timeout causes a "rapid stop" of the drive.
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,
• Via reset service of the identity object, class 0x01, instance 0x01, undetermined at-
tribute,
• Or with a restart of the MOVIPRO
®
unit.
INFORMATION
The set process data length influences the process data lengths of both the polled I/O
and the bit-strobe I/O messages. The process data length of the bit-strobe I/O mes-
sages is max. 4 process data words.
• If the set value for the process data length is smaller than 4, the value is adopted.
• If the set value for the process data length is larger than 4, the process data length
is automatically limited to the value 4.
