Yaskawa SmartTrac DeviceNet Card - Manual (Page 23)

SMART TRAC DeviceNet Card
Technical Manual 3554-0070 Testing Card Installation
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19
Testing Card Installation
Testing the Network
Once installed, check the on-board indicator lights. Normally, both LEDs should
be illuminated green and steady (not flashing), indicating the program is loaded
and running, it is an active participant in network activities, and that polled
connections are established with slaves.
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To properly test your DeviceNet network, perform all of the following
steps below in sequence, since some tests require that previous tests
were successful:
NOTE: Do not perform these tests while the system is operating. There must not
be any communications activity.
1. Ensure all devices are installed.
2. Check the resistance from CANH to CANL at each device
•
If the value is > 60 ohms there could be a break in one of the signal
wires or missing network terminator(s)
•
If the value is < 50 ohms look for; a short between the network
wires, extra terminating resistor(s), faulty node transceiver(s) or
unpowered nodes
3. Power-up all power supplies. Connect a DC ammeter (16 amps max)
from DC common to the shield at the opposite end of the network from
the power supply. There should be no significant current flow. This test
can also be performed at the end of each drop if practical.
•
If there is no current, the shield is broken or the network is
improperly grounded
•
If the power supply is in the middle of the network, do this test at
each end
4. Break the shield at a few points in the network and insert a DC
ammeter
•
If there is current flow, the shield is connected to DC common or
ground in more than one place (ground loop)
General Test
Parameters
Network Termination
& Signal Wires
Shield
Grounding