Sporadic communication interruption to a DNP3 outstation when using the DNP3_TG driver

Sporadic communication interruption to a DNP3 outstation when using the DNP3_TG driver

Summary

Under specific circumstances the communication with a DNP3 outstation using the DNP3_TG driver would get interrupted when the DNP3_TG driver receives a specific multi-fragment response. Variables would become INVALID for a short moment before communication resumes normally. This occurs even though the physical link is not disrupted.

This behaviour may be observed more often with larger points databases in the outstation after the DNP3_TG driver issues an integrity poll.

Description

Under specific circumstances the communication with a DNP3 outstation using the DNP3_TG driver would get interrupted when the DNP3_TG driver receives a specific multi-fragment response. Variables would become INVALID for a short moment before communication resumes normally. This occurs even though the physical link is not disrupted.

This behaviour may be observed more often with larger points databases in the outstation after the DNP3_TG driver issues an integrity poll.

Solution

An issue has been addressed where multi-fragment responses that contain a frame where the application layer sequence counter reaches 15 would cause an error in the driver. Now the driver correctly handles the overflow of the application layer sequence counter also in multi-fragment respsonses.

Information

Error message that is logged:

"Response Sequence error" FC 'RESPONSE', FIR '0', Sequence '0' (Expected '16')



Issue Number: 34759
Fixed on Date: 24.8.2015
Versions: 7.20 0 BUILD 22047 | 7.50 0 BUILD 25796