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Troubleshooting Racks and Units Section 11-3
CJ Long-distance Expansion Racks
Symptom Cause Remedy
CPU Unit won’t operate. (No
response to Programming
Devices and no CPU Unit
indicators are lit.)
(1) Power is not turned ON to an Expansion
Rack.
Turn ON power to all Expansion Racks.
(2) An Expansion Rack is not connected
correctly.
Recheck the connections and configuration
using information in 2-3-3 CJ-series Expan-
sion Racks, 3-5 I/O Control Units and I/O
Interface Units.
(3) An I/O Connecting Cable is not wired
correctly.
Reconnect the I/O Connecting Cables in the
correct order for output and input connec-
tors.
(4) A Unit is faulty. Gradually remove/replace Units to deter-
mine the Unit that is faulty, including the
Power Supply Unit, I/O Units, I/O Control/
Interface Unit, and I/O Connecting Cable.
Expansion Rack not
detected.
(1) A Terminator is not connected. If the TERM indicator is lit, connect a Termi-
nator.
(2) An Expansion Rack is not connected
correctly.
Recheck the connections and configuration
using information in 2-3-3 CJ-series Expan-
sion Racks, 3-5 I/O Control Units and I/O
Interface Units.
(3) A Unit is faulty. Gradually remove/replace Units to deter-
mine the Unit that is faulty, including the
Power Supply Unit, I/O Units, I/O Control/
Interface Unit, and I/O Connecting Cable.
I/O bus error or I/O verifica-
tion error occurs.
(1) An I/O Connecting Cable or Terminator
connection is faulty.
Check that I/O Connecting Cables and Ter-
minators are connected correctly.
(2) Expansion cable is not wired correctly Rewire the terminals using the correct OUT-
IN sequence.
(3) Noise or other external factor. Separate all cables from possible sources of
noise or place them in metal ducts.
(4) A Unit is faulty. Gradually remove/replace Units to deter-
mine the Unit that is faulty, including the
Power Supply Unit, I/O Units, I/O Control/
Interface Unit, and I/O Connecting Cable.
Cycle time is too long. (1) A CPU Bus Unit that is allocated many
words (e.g., Controller Link Unit) is
mounted to a CJ Long-distance Expan-
sion Rack.
Move the CPU Bus Unit to the CPU Rack.
(2) A Unit is faulty. Gradually remove/replace Units to deter-
mine the Unit that is faulty, including the
Power Supply Unit, I/O Units, I/O Control/
Interface Unit, and I/O Connecting Cable.
I/O Control Unit and I/O Inter-
face Units do not appear on
CX-Programmer I/O table.
This is not an error. These Units are not allo-
cated I/O words and thus are not registered
in the I/O tables.
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