How to deal with an invalid measurement

At a Glance

Invalid measurement information is available to the user, in addition to diagnostics. It is used to detect a loss of counting or measurement data.

This fault management, which is similar to latching, is provided in all counting modules.

Fault context

Faults can be indicated by:

a cold start or warm restart of the application,
a fault on counting input:
- a power supply fault or a break in the sensor line (proximity detector or encoder),
- a series frame transmission error (TSX CTY 2C),
- a specific absolute encoder fault (TSX CTY 2C),
exceeding the capacity of the counting register.
exceeding the speed threshold (TSX CTY 2C).

In this case the contents of the counting register cannot be used and counter outputs are set to 0. If this happens, the Invalid measurement INVALID_MEAS (%IWr.m.c.2.7) bit is set to 1.

When the register is initialized or re-initialized by presetting (or reset) and as long as none of the faults above are still present, the Invalid measurement bit switches to 0.

Notes

The Invalid measurement bit set to 1 does not give any information about the fault which caused it. To find this out, the project must examine status words %MWr.m.c.2 and 3, as long as the fault is still there (TSX CTY 2C).
Masked faults do not trigger the Invalid measurement indicator (TSX CTY2C).

How to manage the incident

The procedure for managing and removing the invalid measurement by the project is as follows: