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FM-531HD / May 2013
G E N E R A L I N F O R M A T I O N
General Purpose Interface (GPI)
The FM‑531HD is equipped with eight General Purpose Input (GPI) control input
ports on the rear female DB‑9 connector. All GPI connections are optically‑isolated
to prevent external ground loops and to prevent dangerous voltages from being intro‑
duced into the processor. Further, the GPI inputs accept DC voltages of either polarity,
easing interfacing in the field.
The eight GPI inputs are hard‑coded in software to activate the first eight preset
slots.
GPI
The GPI interface provides eight separate General Purpose Inputs, sharing a com‑
mon return. The connector is a female DB‑9 connector with the following pin assign‑
ments. Note that all pins are isolated from FM‑531HD internal circuitry!
Pin 1 – GPI COM (‑)
Pin 6 – GPI 1 IN (+)
Pin 2 – GPI 2 IN (+)
Pin 7 – GPI 3 IN (+)
Pin 3 – GPI 4 IN (+)
Pin 8 – GPI 5 IN (+)
Pin 4 – GPI 6 IN (+)
Pin 9 – GPI 7 IN (+)
Pin 5 – GPI 8 IN (+)
Processing Presets
The FM‑531HD audio processor comes equipped with several dozen factory presets
and can hold a total of 80 presets in its onboard memory. Additional customer‑created
presets may be saved within the processor’s onboard memory until all preset storage
slots are full. An unlimited number of presets can be stored on the PC that hosts the
Windows‑based remote control GUI software.
In order to prevent clicks and pops when presets are changed, preset parameters are
slewed between the current parameter values and those of the new preset whenever a
new preset is taken. Because of this, when changing presets, especially between pre‑
sets that are tuned quite differently, it may take several seconds for the new settings to
completely settle in. It is important to remember this concept; the FM‑531HD’s preset
switching is designed to make it as unobtrusive as possible and therefore parameter
changes are not instantaneous. This factor must be taken into consideration whenever
switching between presets in order to compare them!
When a preset has been recalled and has not been modified the preset’s name is
displayed in green text within the GUI’s current preset window. If changes to the pre‑
set have been made its name will be displayed in red text instead of green. Once the
modified settings have been saved back to the processor’s hardware the preset name
will again be displayed in green.
Factory pre‑sets can be readjusted and saved to new names in order to create a
completely different air sound. The factory presets are write‑protected and changes
made to them cannot be written back to the same memory location. Factory presets
Summary of Contents for FM-531 HD
Page 2: ...Technical Manual Wheatstone Corporation May 2013 FM HD Digital Audio Processor FM 531hd...
Page 122: ...page A 2 FM 531HD May 2013 A P P E N D I C E S Appendix A General Specifications A 3 Contents...
Page 128: ...page A 8 FM 531HD May 2013 A P P E N D I C E S Appendix B FM 531HD GPI Interface A 9 Contents...