Yaskawa DeviceNet Option Card CM05x - Manual (Page 11)

Introducing the DeviceNet Network 1-6
DeviceNet Option Board
Yaskawa’s DeviceNet Option Board appears as one node on the network. The Option Board must be installed
into each Drive that will be communicating on the DeviceNet network. The Option Board is powered from both the
+24Vdc DeviceNet network power and the Drive.
When connected to the DeviceNet network, the Drive communicates on the network using a Master/Slave
relationship. The Master is a device that gathers and distributes I/O data for the process controller. Slaves are
devices from which the Master gathers I/O data and to which the Master distributes I/O data.
On a DeviceNet network, a Master device is said to “own” a Slave device. A Slave device can be “owned” by
only one Master. A Slave device cannot initiate communication transactions unless it has been told to do so by
its Master. A Master scans its Slave devices based on a scan list that it contains.
The Option Board acts as a DeviceNet Slave device. With respect to the network, the Option Board is
considered to be a Group 2 Only Server.
By definition, a Group 2 Only Server device is UCMM incapable. A Group 2 Only Server uses DeviceNet’s
Predefined Master/Slave Connection Set to establish communications. A Group 2 Only Server can transmit and
receive only those messages defined by the Predefined Master/Slave Connection Set. (Volume I of the
DeviceNet Specification fully defines Group 2 Server Devices). Since the Drive acts a DeviceNet Slave device, it
will respond to message commands issued by a DeviceNet Master device. With respect to the network, the
Master is a Group 2 Client or a Group 2 Only Client.