8
Functions Section 1-2
1-2 Functions
1-2-1 I/O Unit Interface Specifications
Item Specification
Communications method Special protocol
Number of I/O Units 8 Units max.
Maximum number of points Total inputs/outputs: 1,024 points (bits)
Communications dis-
tance
Total length 3 m max.
Between Units 1 m max. (Cable included with Unit is
40 mm.)
Communications power supply Supplied from the Communications
Unit to the I/O Unit (0.4 A max.)
Relationship to DeviceNet After the I/O Unit interface is estab-
lished, DeviceNet communications con-
tinue normally, even if an error occurs
on the I/O Unit interface.
Addresses Automatically recognized when the
power to the Communications Unit is
turned ON.
I/O configuration Automatically recognized when the
power to the Communications Unit is
turned ON. If the configuration is
changed while the power supply is ON,
a configuration error will occur.
Self-diagnostic func-
tions
Configuration errors The I/O Unit configuration is constantly
checked while power is supplied. If a
mismatch occurs while the power is
turned ON, I/O refreshing for all I/O
Units is stopped.
Special I/O Unit
errors
Errors are detected in the Special I/O
Units (Analog Input Units, Analog Out-
put Units, Temperature Input Units, and
Counter Units) on the I/O Unit interface.
I/O Unit interface
errors
Communications stop when there is no
communications response from an I/O
Unit.
Communications stop when there is no
specific response from the last I/O Unit
(terminator).
Communications stop when nine or
more I/O Units are connected.
Power supply over-
load to I/O Units
The power supply to the I/O Units and I/
O refreshing for all I/O Units are
stopped when the power supply to the
I/O Units through the Communications
Unit exceeds 0.4 A.
Error detection Frame error check; CRC-CCITT check
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