Hi,
We are looking to configure an ABR channel on an X90 and as such I was just looking to get some additional information on the function of the “enable reference” input when an ABR counter is configured.
I can’t really find any information about it in Automation Help, other than this mention in the X90 Function Description (484bd6b4-2231-4e41-8e9f-bbb3a495473d).
Thanks!
Hello Jackson,
The Enable Reference is likely referencing a homing enable switch. There is similar functionality on the X20 counter modules (ex. X20DC1196). Below is the relevant section of the AS Help from the X20DC1196 Functional Description.
ABR incremental encoder
Homing
After switching on the power supply, the incremental encoder only measures changes compared to the switch-on position. For many applications however, knowledge of the absolute position is required. For this reason, most angular encoders output a reference pulse (zero pulse, reference mark) once per revolution on a third output (reference signal R). After switching on, the encoder must be rotated until the reference pulse has been detected. The absolute angle is then available after one revolution at the latest. Positioning systems with incremental encoders perform “homing procedures” to an external position sensor (e.g. limit switch) after switching on. From this point, the next reference pulse of the incremental encoder is used as an accurate reference point.
Source: B&R Online Help (br-automation.com)
In short, setting the enable reference channel will home the encoder to ‘0’ at the next reference pulse.
That would makes sense. Shame it isn’t in the documentation for the X90, but thanks for your help!
