Issue
Explanation of the MBP_MSTR error code Hex values of  5050, 5055 and 5056
 
Product Line
140NOE77101, 140NOE77111, 140CPU65xxx
 
Environment
Unity Pro, Concept, ProWORX 32
 
Resolution
 The error code Hex values of 5050, 5055 and 5056 are all similar Ethernet TCP errors. But they do identify where in the TCP connection process the error is occurring.

The error 5050 Is defined as No Network resource. This is pretty much correctly stated. It indicates that the TCP stack does not have any resources free to open the TCP connection. It has a secondary cause in that the module internally, doesn't have a buffer to use to bring the message across from the backplane to the stack. This is that pool of resources that we refer to when we say the module has a pool of 64 connections that are shared between the client and the server functions.

The error 5055 is defined as No Remote Resources- This indicates that the NOE tried to open a connection to the remote device (Target) and that device either did not respond or reset the connection. This also has the added issue that as the EF's keep executing for a device that is not present (not answering) The error will gradually propagate across all connections.

Lastly, The error 5056 defined as Non Operational TCP connection. This is also pretty accurate. The module cannot establish a connection to the device. Often this is seen when a device is not present on the wire when the block starts. It tries to ARP for the address but gets no response or, it simply cannot establish a connection (Port 502 closed). This also can be seen if the Master and Remote Ip addresses are not on the same Network/Subnet address range.