Festo CESA-GW-AS-CO, Installation And Operation Manual, Page: 55 / 83

CESA-GW-AS-CO Description
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7. Operation as CANopen Node
In this chapter you will learn all about operating the AS-i/CANopen Gateway in a
CANopen network. The AS-i/CANopen Gateway supports the CANopen protocol
for data exchange.
The following functions are available via CANopen communication:
•
Reading AS-i input data
• Writing AS-i output data
• Reading all the flags of the execution control,
plus the flags "slave 0 detected", "automatic programming permitted", "auto-
matic programming available", "offline ready"
• Setting off important functions of the host interface:
"offline phase on/off", "enable/disable automatic addressing" and "configura-
tion mode on/off"
The CANopen communication can be subdivided into process and service data
communication. Service data messages are used for read and write access to all
entries of the object dictionary of a device. The main usage of this facility is de-
vice configuration. By means of process data messages the real-time data trans-
mission is performed.
The objects have following properties:
• Process Data Objects (PDO):
• Maximum 8 byte long
• Cyclic or event driven transmission
• Differentation between sending (max. 512) and receiving PDOs (max.
512)
• PDOs reserve its own identifier in the CAN network
• Binary AS-i process data of the A and B slaves of circuit 1 are laid on
the 8 default PDOs
• Service Data Objects (SDOs):
• Length as you like
• Cyclic transmission
• SDOs of a device are grouped in the object directory
• Mailbox is laid on a (server) SDO, 36 byte length
The main features of "Process Data Objects" (PDOs) and "Service Data Objects"
(SDOs) are shown in the table below.
Process data objects (PDOs) Service data objects (SDOs)
used for real time data exchange provide access to a device object dictio-
nary; each SDO establishes a peer to peer
service communication channel.
typically high priority messages low priority messages
synchronous and asynchronous message
transmission typically transmitted asynchronously
cyclic and acyclic transmission typically acyclic transmission
Tab. 7-4.