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(2) Communication with Slave Devices Aborted
When the 7-segment LED indicates an abnormal code, remove the cause of the trouble by
referring to "6.2 Indications of the 7-Ssegment LED."
Checking objects
DN211 Check the T2/T2E/T2N side power-supplies.
Check the connection of the network cables (mis-wiring, disconnection).
Refer to "3.4 Connection with the Network."
Check the node address setting (for node address duplicated).
Refer to "3.2.2 Rotary Switch for Node Address Setting."
Check the setting of the network communication rate (for the same
communication rate).
Refer to "3.2.1 DIP Switch for Setting Operation Mode / Communication Rate."
Check the local node parameter setting and the scan list.
Refer to "4.6.3 Parameter Setting Request (local node)" and "4.6.4 Parameter
Setting Request (slave device)".
Slave device
Check the slave devices for normal operation by referring to the slave device
description.
Check the slave device main unit for the power.
Check the connection of the network cables (mis-wiring, disconnection).
Check the node address settings (for node address overlapped).
Check the network communication rates (for the same communication rate).
Check setting items specific to individual slave devices.
Network Check the terminal resistor on both ends of the trunk cable (121Ω).
Check the maximum network length specified.
Refer to "1.2.2 Trunk Line/Drop Line and Maximum Cable Length."
Check the drops cable length (less than 6 m).
Check the total extension of drops cables.
Refer to "1.2.2 Trunk Line/Drop Line and Maximum Cable Length."
Check the network power mechanism and the power capacity.
Refer to "3.5.1 The Network Power Mechanism" and "3.5.3 The Network
Power Unit (24vdc)."
Check the grounding of the network cables.
Refer to "3.5.4 The Network Grounding."
(3) Overrun Errors Occur
An overrun error occurs when data slave devices transmitted cannot be received by the DN211
(the number of overrun error times is stored at 02C5H in the RAS information area).
How to Solve Overrun Error:
1) Lower the network communication rate when overrun errors occur.
(500 kbps → 250 kbps → 125 kbps)
2) Set the polling transmission mode to "1" at local station parameter setting request
when the polling slaves and bit strobe slave devices have been intermingled.
(waiting for polling response after polling request by a slave device is issued)