Sigma - How does a UNC controller handle log data when comms to the server has failed.

Issue

This article clarifies what a Sigma UNC controller does when logging is going on and comms to the server has been lost.

Product Line

Satchwell Sigma

Environment

Sigma - All versions

Cause

When a sigma controller is logging, during normal operation the data is uploaded to the logging database at various intervals. These uploads are generally controlled by the UNC controller. If comms to the server is lost then the data is stored in RAM until comms to the server is re-established. The resolution details how this happens and what the limitations are.

Resolution

In the controller, after all files have been downloaded, the Alarm buffer is created. The Alarm buffer holds the queue of alarms and logs being sent to the server and can hold up to 500 entries.

Then memory is allocated to the Logging buffer which stores partially complete logging data. It is allocated memory as follows:

 

First series controllers (532, 496/596, IC1):

75% of the remaining memory

ARM 7 series controllers (632, 696/796, IC3):

512kB

 

The Logging buffer contains 138-byte Tracks with one Track for each logged object. Log records are added to the Track as they occur and the Track is transferred to the Alarm buffer when full.

The maximum number of log records that a Track contains depends on the type of object and the type of log as follows:

 

Operation

Object Type

Records per track

Timed

Analogue

25

Timed

Digital

100

Event

Analogue

14

Event

Digital

32

Alarm/report (as a log)

Any

28

 

Partially full Tracks can be moved to the Alarm buffer (and thus automatically to the server) by selecting Diagnostics > Options > Retrieve Logs.

Where an Autodial connection is used, a telephone call is initiated when any alarm (non opportunistic) or log is placed in the Alarm buffer.