CP 1430 TF stop red led on

Kindly, we have the following module with a  stop red led on .  What could be the problem ?  How can we diagnose this module ?  It is installed on a S5 135u/155u rack next to a cpu928b .  Thank you  

6GK1143-0TA02 , SIMATIC NET CP 1430 TF Communications processor for Connection ... to Industrial Ethernet Basic-Version