Ndrive HL User’s Manual
Technical Details
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3.2. Position Synchronized Output (PSO) / Laser Firing
The Ndrive HL includes a Position Synchronized Output (PSO or Laser Firing) option.
This feature may be programmed to generate an output synchronized to axes positions,
based upon a user-defined trigger condition, most typically, but not limited to firing a
laser. The Ndrive HL offers three levels of laser firing, single axis (std.) and two and
three axis. Trigger signals may be derived from the primary encoder channel, secondary
encoder channel, either of the two optional SSI Net ports or a software trigger. Both SSI
Net ports may provide axes encoder signals or marker signals to/from another Ndrive HL
at a maximum of a 20 MHz. data rate (50 nsec. minimum edge separation). Single axis
tracking is limited to a 20 MHz. data rate and multi-axis to a 5 MHz. tracking rate. The
PSOTRACK command may be used to scale the encoder input signal to limit the
maximum tracking rate. The synchronized output pulse is solely generated within
sophisticated and versatile high-speed hardware, allowing minimal delays between the
trigger condition and the output. Single axis PSO laser firing latency is 200 nanoseconds.
–DUALPSO and –TRIPLEPSO laser firing latency is 275 nanoseconds, not including the
propagation delay of the output device. Refer to Figure 3-6 for a basic single-axis block
diagram of the PSO capabilities, or Figure 3-4 and Figure 3-5 for a more detailed block
diagram of the multi-axis capabilities that also apply to single-axis firing. The output
may be either an open-collector output (dedicated PSO output or user output 11) or a
differential RS-422 output. The opto-isolated output is available in three different
configurations as shown in Table 3-10. Additionally, the PSO options provide Data
Capture and Data Update capabilities, also shown in Figure 3-4 and Figure 3-5.
For
programming information, refer to the Nview HMI Help.
Table 3-9.
PSO Encoder Signal Sources and Pre-Scaling Methods
Encoder Signal
Source
Max. Data Rate
(w/o pre-scalar)
Encoder Input
(pre-scalar)
Encoder Output
(pre-scalar)
Primary Encoder
32 MHz.
PSOTRACK
Command
CfgFbkEncQuadDivider axis
parameter (MXH only)
Secondary
Encoder
32 MHz.
PSOTRACK
Command
None
SSI Net Ports 1
and 2
20 MHz.
PSOTRACK
Command
CfgFbkEncMxhSetup axis
parameter
Table 3-10.
PSO Output Sources
PSO Output Type
Maximum
Frequency
Standard or
Option
Requires User
Isolation
High Speed Opto-Isolator (J301)
Table 4-13
-IOPSO option
No
Opto-Isolated Output 11 (J205)
1 kHz
Standard No
RS-422 Marker output on Sec.
Encoder (J205)
10 MHz
Standard Yes
The pre-scalar in the block diagram is used to normalize the resolution of axes with
different machine step sizes or to scale down (divide) the maximum input frequency to
the PSO tracking hardware. The PSO hardware operates in machine counts, so all axes
must be scaled, or normalized to like units. This allows a trigger to be generated from a
true vectorial position change. Each of the three possible tracking channels has a pre-
scalar, which may be used to divide the number of encoder counts on that channel. Each
pre-scalar defaults to 1 and may divide the input feedback pulses by up to 1,023.
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