Mach-DSP User’s Manual
Document Number: MACH-DSP-9021
Page 20
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3.5
Test and Thermistor interface
The Test and Thermistor interface connector is located on the right / front side of the
board. This connector provides 1K-resistor-buffered analog output signals that may be
used during servo tuning, and may also be monitored by external equipment if desired.
This connector may also be used to connect a thermistor as described below. The
connector pin functions for the test interface connector are provided in Table 3.5.
Table 3.5: Test Interface
Pin
Function
1
Ground
2
X-axis Position (not scaled)
3
X-axis Command input (after filter)
4
X-axis Motor drive current (1 V/A)
5
X-axis AGC drive voltage (negative)
6
Ground (usually used for thermistor)
7
User-defined analog output 1
8
User-defined analog output 2
9
User-defined analog output 3
10
Ground
11
Y-axis Position (not scaled)
12
Y-axis Command input (after filter)
13
Y-axis Motor drive current (1 V/A)
14
Y-axis AGC drive voltage (negative)
15
NTC Thermistor (10K
β
=3300 nominal)
16
User-defined analog output 4
17
User-defined analog output 5
18
User-defined analog output 6
Mating Connector Housing:
MOLEX Micro-Fit Jr: 0430251800
Mating Connector Pins:
0430300001 through 0430300012
Specified Wire Size:
AWG #20-#30, depending on pin type
Position, Command, Current and AGC signals
The Test Interface connector includes a number of signals that are referred to as
“analog”, but the only truly analog signals are the Position, Command, Current and AGC
outputs for both the X- and Y-axes. These are measured and processed purely in the
analog domain. As such, they offer maximum resolution in both time and range.
The Position signal has a scale factor that varies somewhat from scanner to scanner,
but tends to be approximately 2.45 mechanical degrees per volt for systems that are not
customized. The Command signal output is a direct reflection of the Mach-DSP analog
command input. The Current signal has a fixed scale factor of 1-volt-per-amp. The AGC
signal is a reflection of the voltage seen by the galvo position sensor LED driver.