---
title: How to eliminate the problem of IO-LINK master module quickly?
description: Master fault descriptions
---

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# How to eliminate the problem of IO-LINK master module quickly?

## Master fault descriptions

If we encounter a problem when it's in use, we can first observe the large LED on the module of the Balluff master:

 

![IO-LINK方案2](https://kb.innovatingautomation.asia/hs-fs/hubfs/Knowledge%20Base/Simplified%20Chinese/Image/%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%97/IO-LINK%E6%96%B9%E6%A1%882.png?width=280&name=IO-LINK%E6%96%B9%E6%A1%882.png)

**US:**

- Green means the input voltage is normal
- Red flashes means the input voltage <18v

 

**UA:**

- Green means the output voltage is normal
- Red means the output voltage <118
- Red also means the output voltage <11V

 

**SF:**

- No light means no error
- Red Indicates watchdog timeout channel, general or advanced diagnosis exists or system error,
- Red flashing indicates that the service DCP signal is started via the bus

 

**BF:**

- No light indicates no error
- Red indicates slow physical link speed; or no physical contact
- Red blinking means no data exchange or configuration

 

**100:**

- No light means communication rate: 10Mbit / s
- Yellow means communication rate: 100Mbit / s

 

**LK:**

- Green means data exchange

 

![网络模块6](https://kb.innovatingautomation.asia/hs-fs/hubfs/Knowledge%20Base/Simplified%20Chinese/Image/%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%97/%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%976.png?width=370&name=%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%976.png)

 

**The second is the Port status display:**

**Standard port:**

- Off indicates that the input or output pin status is 0
- yellow is the input or output pin status is 1
- two flashing red LEDs indicate the sensor power supply is short-circuited or  
  the red pin 2/4 is short-circuited to pin 3 or there is no high signal at the diagnostic input.

 

![网络模块7](https://kb.innovatingautomation.asia/hs-fs/hubfs/Knowledge%20Base/Simplified%20Chinese/Image/%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%97/%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%977.png?width=391&name=%E7%BD%91%E7%BB%9C%E6%A8%A1%E5%9D%977.png)

**IO-LINK port status:**

- Green indicates that the IO-Link communication connection is activated,
- Green flashing indicates that there is no IO-Link product connection or wrong IO-LINK device,
- Green rapid flashing indicates that during data management, IO-Link pre-operation,
- Red rapid flashing means failed verification / IO-Link data length configuration error, data management failure / data management device error,
- Red means IO-Link short circuit, pin 4 to pin 3.

 

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