Codesys engineering tool failed to discover IO devices but able to discover vPLC

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. Codesys management system is called engineering tool.

This article is about the case that Codesys engineering tool failed to discover IO devices although 
it can communicate with vPLCs.

Environment

4.2.x

Resolution

There is difference about management connectivity between Siemens and Codesys management system.
Siemens uses the network interface that is connected to Profinet to communicate with vPLCs and IO devices. 

However, Codesys engineering tool doesn't have a network interface for Profinet. It uses the management port to communicate with vPLC. Due to this, the Codesys Engineering is not required to be on a IvS, but it needs to be on the same NSX segment with vPLCs. 

For this issue, Codesys engineering tool has a connectivity with vPLC, so the cause is in the network between vPLC and IO devices. Verify the network connectivy by capturing the packets on vPLC port.