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Troubleshooting
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372 SPU 780 01EMAN May 2002
Modbus Plus
Modbus Plus
Communications
for Concept Exec
Loader
When using Modbus Plus communications and the interrupt is NOT "5C", you must
add the following line to the "modicon.ini" file located in the Windows folder:
Under the heading: [Ports]
MBP0 (or MBP1) = interrupt 5D
Modbus Plus
Indicator
On most Modbus Plus devices, a green LED flashes a repetitive pattern indicating
the communication status of the node. The patterns are:
Six flashes per second: Normal operating state. The node is successfully
receiving and passing the token. All nodes in operation on the network should be
flashing this pattern.
One flash per second: Node is offline after just being powered up or there is
another node on the network with the same address (duplicate addresses are not
allowed). The node remains in this state for five seconds, then attempts to go to
its normal operating state.
Two flashes, then OFF for two seconds: Node is hearing the token being passed
among other nodes, but is never receiving the token. Check the network link for
an open or short circuit, or defective termination.
Three flashes, then OFF for 1.7 seconds: Node is not hearing any other node. It
is periodically claiming the token, but finding no other node to which to pass it to.
Check the network link for an open or short circuit, or defective termination.
Four flashes, then OFF for 1.4 seconds: Node has heard a valid message from
another node that is using the same address as this node. The node remains
offline in this state as long as it continues to hear the duplicate address. If the
duplicate address is not heard for five seconds, the node then changes to the
pattern of one flash every second.