Appendix C: QSBX/40 Module
TMC 188/40 Motion Control Module
Delta Computer Systems, Inc. 360/254-8688
84
QSBX/40 Block Diagram
Input Buffer
And Isolation
Quadrature
Home
Limit
Signal
Conditioner
Preset
Counter
Buffer
Home
Qualify
Control
Logic
iSBX
Bus
Important Considerations When Using Quadrature Encoders
DIRECTION Parameter
The DIRECTION parameter must be set to zero. This forces the Transducer Counts to increase
when the axis is extending. To reverse the direction, reverse the A and B signals from the
quadrature encoder and reverse the drive output leads from the TMC 188/40-(T)Q.
SCALE Parameter
The way the SCALE parameter is used by the TMC 188/40-TQ changes when a quadrature
encoder is selected. The method used to calculate position units for a quadrature axis is given
below. See pages 88 and 89 for examples of the SCALE parameter.
With quadrature encoders:
ACTUAL POSITION = (Transducer COUNTS x 1000 / SCALE) + OFFSET
With Magnetostrictive Transducers:
ACTUAL POSITION = (Transducer COUNTS x SCALE / 32768)
XOR DIR OFFSET