TIA indicates that vPLC stops with Safety Program error or time provider time exceeds

Products

• VMware NSX

Issue/Introduction

Industrial vSwitch (IvS) is used for manifacturing use case. There are many IO hardware devices in an automotive fatory, and there are virtual Programmable Logic Controllers (vPLC) to control the IO devices. For the communication between vPLC and IO devices,low latency and IvS is required. In addition to vPLC and IO devices, there is a management system for vPLCs and IO devices. Currently IvS manifacturing solution support two vPLC vendors, Siemens and Codesys. Siemens management system is called Totally Integrated Automation (TIA). TIA requires to have a time server appliance to get the precise clock. 

This article is about how to troubleshoot in case that vPLC stops working.

Environment

4.2.x

Resolution

In the case that vPLC stops with Safety Program error or time provider time exceeds, this could be a time server related issue. As a first step, ensure that the time server application is running and vPLC has the right interface configured to receive clock inputs from the time server.

If the time server application is running and vPLC network interface configuration is correct, you should verify if there is delay of time inputs at the receiving end of vPLC. 
Collect the packets both at the source switch port (time server) and the destination switch port (vPLC) on the IvS, then analyze the time stamps.

Get the time provider switch port id, on the host where the time provider is running the command “net-stats -l”. On the same host, capture packets at the source time provider switch port:

Login to the host where vPLC is running and get the port ID for vPLC by “net-stats -l” command. capture the packets at this destination switch port.

Verify that subsequent packet intervals are almost the same at both source and destination. If there is a significant delay, report to the PLC vendor.