Rockwell-automation 1771-QA Stepper Positioning Assembly User Manual Bedienungsanleitung PDF herunterladen (Seite 36)

3–14 Programming and Operation

Publication 1771-UM002A–EN–P – May 2000

Figure 3.9

Offset and Preset Words

17 10 07 00

Data Table

999

0000

MCW

Offset

MS Preset

LS Preset

0 = Add

1 = Subtract

1 = Assert

Initialization

Preset

0 = Move

Preset

10522

The moves affected by the offset will be those stored in the working

and storage moveset when the command is received. If additional

movesets have been programmed, the offset command must be

re-enabled when additional movesets are transferred to the stepper

controller module.

Preset Word

The preset word can store values that serve two functions. One

function, initialization preset, is used by the stepper controller

module to define the starting point value of the positioning profile.

The other function, move preset, can be used to extend one or more

moves of the profile beyond the 999,999 pulse (position) limit of the

stepper controller module. In either case, the preset word can be

loaded with the necessary value, the function enabled and another

value loaded as needed. When used, the preset value becomes the

new position reference of the profile.

The preset can be any value between 0 and 999,999. Preset data is

contained in two words, one for the most significant (MS) 3 digits,

the other for the least significant (LS) 3 digits (Figure 3.9). Preset

values are entered in BCD in bits 00-13. Bits 14-17 in the LS preset

word and bits 14-16 in the MS preset word are undefined and must

be loaded with zeros. Bit 17 of the MS preset word is the assert bit

for the initialization preset.

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Rockwell-automation 1771-QA Stepper Positioning Assembly User Manual Bedienungsanleitung Seite 36