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Rockwell Automation Publication 856T-UM001B-EN-P - April 2021
Chapter 6 Class A IO-Link Master Connection Consideration
For example, the total current consumption for an IO-Link stack light with
three 856T steady light modules green-amber-red (bottom to top) is:
Since the maximum current per port in the 1732E-8IOLM12R IO-Link master is
500 mA, the stack light configuration in the previous example can work within
the master parameters.
Inrush Current Calculation
To minimize total inrush current seen by the IO-Link Master, the 856T-B24LC
module staggers the turn on time of the connected modules. For seven light/
sound modules in a stack light arrangement, this time does not exceed 60 ms.
The inrush current values for each standard 856T light/sound module are
shown in
Since the maximum inrush (1.82 A) at a given time is below the IO-Link master
port (4 A), then this configuration is within the IO-Link master parameters.
Overcurrent Protection
When an overcurrent or short circuit condition in one or more light or sound
modules in the stack light exists, the 856T-B24LC module disables the entire
stack when any of the circuits demands a load current that exceeds 450 mA
(±15%). The first circuit that was detected to cause the short-circuit condition is
indicated by its respective bit number in the Short Circuit Status byte.
The short circuit status bit is only cleared when you attempt to turn the circuit
back ON and the short circuit is no longer present. Since the entire stack is
disabled during a short circuit, the Control Circuit Status (ISDU 0x0134),
reports OFF for all circuits when a short circuit condition exists.
Under a dead short condition, it is possible that the ArmorBlock master port
could be damaged. Therefore, it is recommended to use a 24V DC power supply
that is limited to a maximum current of 5 A.
Total (mA)
= 856T-B24LC +
856T-BT3
+
856T-BT5
+
856T-BT4
Total (mA)
=
30 mA
+
58 mA
+
58 mA
+
58 mA
=
204 mA
IMPORTANT
If a splitter is used to connect the 856T-B24LC module, then the
maximum total current consumption (856T-B24LC light and
sound modules) must not exceed 250 mA.
Stack light config
= 856T-B24LC +
856T-BT3
+
856T-BT5
+
856T-BB4
Inrush of every module
=
0.1 A
0 A
0 A
1.82 A
Summary of Contents for Allen-Bradley 856T-B24LC
Page 6: ...6 Rockwell Automation Publication 856T UM001B EN P April 2021 Table of Contents Notes ...
Page 72: ...72 Rockwell Automation Publication 856T UM001B EN P April 2021 Appendix D Device Status Notes ...
Page 80: ...80 Rockwell Automation Publication 856T UM001B EN P April 2021 Index Notes ...