Packet Error Counters: Overview

Introduction

The Packet Error Counter checks for missing or invalid packets over a SynqNet network. It is used for long-term performance monitoring (i.e. Have any errors occured since startup?). Since communication over a SynqNet network is based upon the sending and receiving of packets, it is important to monitor the data integrity of the system. Packets must be checked to ensure that they are being sent/received properly and that the packets that are sent contain the right information. The Packet Error Counter increments by one for each invalid or missing packet. There are Packet Error Counters on the individual nodes and the controller to check packets on the upstream and downstream cycle. Unlike CRC Errors, packet errors are node-specific (i.e. Nodes only check their own packets and ignore all other packets).

Node

The Packet Error Counter on each node checks to make sure that it received all three of its packets that were sent from the controller during each downstream SynqNet cycle. Each downstream cycle, a node expects to receive a SYNQ, DEMAND, and CONTROL packet. The counter is reset to zero after a hardware reset or can be manually reset in Motion Console. The counter is an unsigned 8-bit value, and saturates at a maximum of 0xFF.

Controller

The controller also has a Packet Error Counter for each node (up to 32 of each). Their function is identical to the node counters except the controller expects to receive two packets (FEEDBACK and STATUS) from each node for every upstream SynqNet cycle. The controller has individual packet error counters for each node, which count the number of upstream packet errors from each node. The counter increments by one for each invalid or missing packet. The counter is reset to zero after a hardware reset or can be manually reset in Motion Console. The counter is an unsigned 8-bit value, and saturates at a maximum of 0xFF.

See Also:

Packet Error Rate Counter
SynqNet Fault Recovery
SynqNet Failure
CRC Error Counter