Yaskawa AC Servo Drives Sigma II Series DeviceNet - Manual (Page 26)

4 WIRING
E-23
„ Basic Precautions
Basic precautions are as follows:
• The communications power supply to the network must be 24 VDC.
• The communications power supply must have a sufficient margin in the capacity.
• Connect the communications power supply to the trunk line.
• If many nodes are provided with power from a single power supply, locate the power
supply as close as possible to the middle of the trunk line.
• The allowable current flow in a thick cable is 8 A and that in a thin cable is 3 A.
• The power supply capacity for a drop line varies with the drop line length. The longer a
drop line is, the lower the maximum current capacity of the drop line will be regardless
of the thickness of the drop line. Obtain the allowable current (I) of the drop line (i.e.,
the allowable current consumption of the drop line and devices connected to it) from the
following equation
I=4.57/L I: Allowable current (A)
L: Drop line length (m)
• If only the communications power supply is turned OFF while the network is operating,
errors may occur in the nodes that are communicating at that time.
„ Location of Power Supply
The following two types of configuration are possible for the location of the power supply.
Nodes on Both Sides of the Power Supply
Nodes on One Side of the Power Supply
Note: The “Nodes on Both Sides of the Power Supply” method is recom-
mended if a single power supply is connected to many nodes.
Power Supply Tap or
T-Branch Adapter
Communications
power supply
NS300
Module NS300
Module NS300
Module NS300
Module
Power Supply Tap or
T-Branch Adapter
Communications
power supply
NS300
Module NS300
Module NS300
Module NS300
Module