A Unity Momentum PLC using MBP_MSTR will not open a connection to a device if that device responds with a Window Size of 0.

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Issue
This resolution explains why a Unity Momentum PLC using MBP_MSTR will not open a connection to a PowerLink G3 Controller.

A 171CBU9809x Unity Momentum using an MBP_MSTR will not open a connection to a PowerLink G3 Controller if the PowerLink replies with a Window Size of 0 in its [SYN, ACK]. Whenever a [SYN, ACK] packet with a Win = 0 is received, the Unity Momentum will respond with a Reset [RST, ACK]. This behavior will continue as long as the Window Size remains 0.

192.168.1.10 = Unity Momentum
192.168.1.120 = PowerLink G3

Product Line
171CBU98090
171CBU98091

Resolution
The issue occurs in Unity Momentum firmware versions less than V1.3.
The issue is resolved in versions 1.3 or higher for the 171CBU98090 and 171CBU98091. The connection will now be established even if the Window Size is 0 in the SYN, ACK.

192.168.1.12 = Unity Momentum
192.168.1.120 = PowerLink G3