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144 ACS 400 User’s Manual

References

References are 16-bit words comprised of a sign bit and a 15-bit integer. A negative reference

(indicating reversed direction of rotation) is formed by calculating the two’s complement from the

corresponding positive reference value.

Reference 1

Holding Register: 40002

Reference 1 can be used as the frequency reference

REF1 for the ACS 400. The signal source of

external reference 1 (

REF1) must be set to COMM and external control location 1 (EXT1) must be

activated. Refer to parameters 1103

EXT REF 1 SELECT and 1102 EXT1/EXT2 SEL.

Reference 2

Holding Register: 40003

Reference 2 can be used as the frequency reference

REF2 for the ACS 400. The signal source of

external reference 2

REF2 must be set to COMM and External control location 2 (EXT2) must be

activated. Refer to parameters 1106

EXT REF 2 SELECT and 1102 EXT1/EXT2 SEL.

Fieldbus Reference Scaling

Fieldbus references are scaled as follows:

Reference 1: 20000 EXT REF1 MAX (Hz, parameter 1105). Scaling Parameter 1104 EXT REF1

MIN is not used.

Reference 2: 10000 EXT REF2 MAX (%, parameter 1108). Scaling Parameter 1107 EXT REF2

MIN is not used.

Fieldbus Reference

Fieldbus reference is selected by setting a reference selection parameter – 1103 EXT REF1

SELECT or 1106 EXT REF2 SELECT – to COMM, COMM+AI1 or COMM*AI1. The latter two

enable correction of the fieldbus reference using analog input AI1. The following table explains

these selections. Note that the analog input value is a percentage value (0-100 %) which can be

seen in parameter 0118 AI1. When the analog input is 50 %, the correction is 0. When the input is

<50 % (>50 %), the correction reduces (respectively increases) the reference used.

Table 25 Correcting the fieldbus reference through analog input.

Parameter Setting Effect of AI1 Value on Fieldbus Reference

COMM None

COMM+AI1 Corrected fieldbus reference = given fieldbus reference + analog input AI1 value

COMM*AI1 Corrected fieldbus reference = given fieldbus reference * analog input AI1 value / 50 %

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