Baumer HMG11 N29 Handbuch - Seite 30

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Note:

Any alteration of the total measuring range during encoder re-parameterization will implicate clearing the

internal preset-offset value. This however has no effect in practice since in this case the position is lost

anyway.

5.6.1.

Preset in standard telegrams

Bit 31 in the 32bit output data word is the preset bit. The lower bits (bit 30...0) hold the right-aligned position

value, which is adopted by the encoder in the preset operation.

The Preset-Bit must be kept set for at least one full I/O bus cycle to be recognized by the encoder. A timer

control of e.g. 10ms or more will do as well. The Preset Bit may stay active for an unlimited period of time

since only a change from „0" to „1" will be evaluated. We recommend however to clear the bit after

completion in order to provide the original status for a subsequent preset operation.

5.6.2.

Preset in PROFIdrive telegrams 81 - 83

A preset operation in control word STW2 requires the PLC having set bit "CP" (Control by PLC). Usually, the

PLC should have this bit set from the beginning when it establishes the Application Relationship (AR).

The „REL" bit in control word G1_STW1 defines whether an absolute or relative preset operation will be

performed. In a relative preset operation, the current position value will be shifted by the signed preset value.

The „PR" bit in G1_STW1 is the preset bit. Upon changing from "0" to "1", it triggers the preset operation.

Once successfully completed, bit "PA" (preset acknowledge) is set in status word G1_ZSW1. The PA bit

remains active as long as the preset bit remains set by PLC.

The preset value is retrieved from the value stored in parameter 65000 (see chapter 7.4.18 „Parameter

65000: Preset Value". In a relative preset operation, the 32bit value is interpreted as a complement on 2, i.e.

„-1" will be saved as „0xFFFFFFFF".

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