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Problems and Countermeasures Section 8-3
Trouble Adding a Slave to
the Network
Use the following table to troubleshoot problems in adding a Slave to the net-
work.
After the MS indicator turns green, the NS
indicator does not flash green - it turns red
immediately.
Restart the faulty Slave Unit after checking the following points.
• Make sure that the Master and Slaves baud rate settings all match. If
they do not match, set all of the baud rates to the same value.
• Check for a node address duplication. If necessary change the node
address settings so that each node has a unique number.
• See the troubleshooting steps below under the error heading: “The NS
indicator lights green but turns red after a short time.”
• Check whether all of the Slaves’ settings are correct.
• If a particular Slave’s NS indicator is always red, replace that Slave.
The NS indicator lights green but turns red
after a short time
or
The NS indicator lights green but starts
flashing red after a short time.
• Restart the faulty Slave Unit after checking the following points.
• Make sure that there are 121- Terminating Resistors connected at
both ends of the trunk line. Connect 121- Terminating Resistors if the
wrong resistance is being used.
• Check whether all of the Slaves’ settings are correct.
• Check whether the communications cables are connected properly.
• Check whether the power supply is set correctly.
• Check all the nodes for broken wires in the communications and power
supply cables attached to the connectors.
• Check whether power is correctly supplied to the network.
• If there is nearby equipment that generates electrical noise, take steps to
shield the Master, Slaves, and communications cables from the noise.
• If an error has occurred with an OMRON Master Unit, refer to the Master
Unit’s Operation Manual. If an error has occurred in a Master supplied by
another maker, refer to the relevant operation manual.
• If a particular Slave’s NS indicator is always red, replace that Slave.
Error Probable cause
Ω
Ω
Error Probable cause
The NS indicator remains OFF. • Check if the baud rate of the Master Unit coincides with that of the Slave
Unit. If the baud rate are different, correct the baud rate of the Slave Unit.
• Check that the Slave’s connector is connected correctly.
• Check whether the communications power supply is supplying 24 VDC.
• Make sure that the Master is operating properly.
When using an OMRON Master, refer to the Master Unit’s Operation
Manual. When using another company’s Master Unit, refer to that Mas-
ter’s user’s manual.
• Check whether the communications cables are connected properly.
• Check whether the power supply is set correctly.
• Check for broken wires in the communications and power supply cables
attached to the connectors.
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