Rockwell Automation Allen-Bradley 856T-B24LC, User Manual, Page: 43 / 82

Rockwell Automation Publication 856T-UM001B-EN-P - April 2021 43
Chapter
5
Power On Self Test (POST)
The 856T-B24LC module runs a self-test routine to check on the health of its
electronic components at powerup.
This read-only diagnostic value (ISDU= 0x0137) is available via the IO-Link
protocol.
Table 8 shows the result/error codes that are associated with this test.
Hardware Fault Conditions
There are three types of hardware fault conditions:
• Non-recoverable
• Critical
• Severe
Non-recoverable
A non-recoverable fault means that MCU flash and/or RAM is corrupted and
the device cannot work anymore, however, the result code may be
communicated using the device status indicator.
Table 8 - Result/Error Codes After POST
Result/Error Code
Decimal (Binary)
Description
Device Hardware
Fault Condition
Recommended Action
0 (0000) Success — —
1 (0001) Firmware image corrupted Non-recoverable Replace the 856T-B24LC module.
5 (0101) RAM test failed Non-recoverable Replace the 856T-B24LC module.
6 (0110) Secondary processor failed Critical
• Check Class B voltage is in specified
range.
• If Class B voltage is present and in range,
replace the 856T-B24LC module.
7 (0111) IO-Link PHY failed Critical
• Check that cordset or patchcord is
properly attached to the IO-link device
and the IO-link master.
• Replace the 856T-B24LC module.
9 (1001)
Accelerometer
communication failed
Severe Replace the 856T-B24LC module.
10 (1010) Serial flash integrity failed Severe Replace the 856T-B24LC module.
11 (1011) Bad Class-A voltage Severe
Verify that Class A voltage is in range and
that the patchcord or cordset is attached
properly.
12 (1100) Bad Class-B voltage Severe
Verify that Class B voltage is in range and
that the patchcord or cordset is attached
properly.