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4. Troubleshooting (PROFIBUS DP)
4.2.3.4 Broken Unit Examination (Dividing Network Examination)
When you cannot quickly find the trouble point due to broken unit, connection failure
including loose connector, or cable partial disconnection, divide the network to find the
trouble point. Verify how error occurrence conditions change while taking the following
countermeasures.
How to Examine
Divide the network to find which station is a cause of a trouble.
Verify that a master can establish communications with the slaves even though one slave is
separated from the network.
After finding the trouble station, check the cables connected to it and replace the unit.
How to Divide
Divide the network by block and check each block.
1. Ensure that the master has no problem by connecting it to its slaves one by one.
(BF/ST: light OFF/green light ON or blinking)
2. Divide the network in the middle of it and check for the communication condition.
(BF/ST: light OFF/green light ON or blinking)
Normal: The trouble point is on the other half of the network.
Error: The trouble point is on the current half of the network.
(Continue dividing the half of the network further to distinguish error part from
normal part.)
3. Check for communication on the block to specify the trouble point.
PLC
Terminating
Resistor ON
Slave
Specify which station is the limit of
the normal communications.
Maste
r
Separate slaves from the network.
Slave Slave
Slave Slave
Terminating
Resistor ON
Terminating
Resistor ON
134 Fieldbus I/O Rev.6