This absolute reference is also calculated here and is displayed as position of the
zero signal in ec31.
Operation of EnDat multiturn encoders with battery buffering
For some designs, such as larger hollow shaft encoders or scale rings with scan-
ning heads, no gearbox can be installed. The multiturn function is then imple-
mented here with a buffer battery which is connected to the encoder. This only
supplies the part in the encoder that is responsible for counting the revolutions,
even if the "normal" main voltage supply to the encoder is switched off.
As long as either the battery voltage or the main voltage supply is above its maxi-
mum value, the counted revolutions are reliable.
If the voltage of the buffer battery (rated voltage 3.6V) is below certain threshold
values, the encoder reports warning and/or error messages.
The multiturn range is dependent on the encoder and min. 65536 revolutions,
whereby the encoder evaluation can only process max. 65536 revolutions from the
encoder.
Only the software-related functions that result from the EnDat protocol for the oper-
ation of these encoders are described here. All hardware-related information (e.g.
battery types, connection, etc.) can be found in the Heidenhain documentation.
6.1.9.1 Battery-specific error and warning messages
The errors for battery-buffered encoders are fundamentally important for the func-
tion of the encoder and the reliability of the position value. Therefore, for resetting,
e.g. with co00 = 128, bit 1 "reset error for battery-buffered EnDat encoder" in ec36
several encoder functions must be set beforehand.
This is to prevent these messages from being accidentally reset and thus over-
looked by an automated error reset (e.g. after each switch-on).
The following battery-specific error and warning messages are described in the re-
spective chapters for error and warning messages, in detail:
- Error message of the encoder evaluation: ec01 = 62 „EnDat: encoder send bat-
tery warning“
- Warning from the encoder: ec19, Bit 3: "Battery charge“
- different alarm bits and operating status error sources from the encoder in ec18.
6.1.9.2 Changing the buffer battery
When changing the buffer battery, the encoder must be connected to the main
power supply. Otherwise, the counted revolutions are lost, which is displayed with
the operating status error source "M Voltage interruption" in ec18.
The battery charge warning can be cleared by switching the encoder type ec16 off
and on again.
6.1.9.3 Zero setting of the revolution counter in the encoder
With bit 2 "clear multiturn rounds for battery-buffered EnDat encoder" of ec36, the
revolution counter in the encoder can be set to zero, i.e. subsequently the counted
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