Control Techniques Digitax ST - Menu 7: Analog I;O

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Menu 7
Digitax ST Advanced User Guide 99
Issue Number: 1 www.controltechniques.com
5.9 Menu 7: Analog I/O
Hardware
The drive has three analog inputs (AI1 to AI3) and two analog outputs (AO1 and AO2). Each input has a similar parameter structure and each output
has a similar parameter structure. The nominal full scale level for inputs in voltage mode is 9.8V. This ensures that when the input is driven from a
voltage produced from the drive's own 10V supply, the input can reach full scale.
Update rate
The analog inputs are sampled every 4ms except where the destinations shown in the table below are chosen, the input is in voltage mode and other
conditions necessary for short cutting are met.
Analog outputs are updated every 4ms except when the source is Pr 3.02, Pr 4.02, Pr 4.17 and Pr 5.03 and high speed update mode is selected. In
high speed mode the output operates in voltage mode. It is updated every 250μs and special scaling is used as described in the table. User scaling is
ignored.
Terminal Input Input modes Resolution
5/6 AI1 Voltage only
12 bit plus sign
(16 bit plus sign as a speed reference)
7 AI2 0 to 6 10 bit plus sign
8 AI3 0 to 9 10 bit plus sign
Terminal Output Output modes Resolution
9 AO1 0 to 3 10 bit plus sign
10 AO2 0 to 3 10 bit plus sign
Input destination Sample rate
Pr 1.36 - Analog reference
250μs
(AI1 subject to window filter. See Pr 7.26 on page 105)
Pr 1.37 - Analog reference
250μs
(AI1 subject to window filter. See Pr 7.26 on page 105)
Pr 3.22 - Hard speed reference
250μs
(AI1 subject to window filter. See Pr 7.26 on page 105)
Pr 4.08 - Torque reference
AI1 – 4ms
AI2 or 3 – 250μs
Output source Scaling
Pr 3.02 – speed 10.0V = SPEED_MAX
Pr 4.02 - torque prod current
10.0V = Kc / 0.45
where Kc is the current scaling factor for the drive
Pr 4.17 - magnetising current 10.0V = Kc / 0.45
Pr 5.03 - output power
The output is the product of the active current and the voltage component in phase
with the active current (vsy x isy).
10V would be produced when:
Active current = Kc / 0.45
Peak phase voltage in phase with the active current = DC_VOLTAGE_MAX / 2