ADLINK LPCIe-8124-C Encoder Card Trigger Configuration Guide

Differential output (not directly listed, but implemented through TRG+/- signals, suitable for long-distance transmission).

4.2 Trigger pulse width programming

Set the pulse high-level duration through software, ranging from 0.1 μ s to 3.2765 ms, with a step size of 0.1 μ s. It is recommended to set at least 1 μ s to ensure reliable response of the device. If connecting optocouplers or relays, it should be extended to milliseconds.

4.3 Trigger Mode

Manual triggering: Software instructions immediately generate pulses for debugging.

Linear comparison trigger: Set the starting position and step size, triggering every time the counter reaches the starting position+n x step size, achieving equidistant triggering.

Table trigger: Pre stored up to 1023 position points, matched in order for triggering, used for any spacing requirement (such as irregularly distributed points on PCB).

Timer trigger: independent of position, generates pulses at fixed time intervals, and simulates position triggering in conjunction with encoder speed.

The trigger output can independently control each channel and supports output inversion (polarity selection) to adapt to the effective level of different devices.

Position Latch function

Each channel is equipped with an external latch input (LTC) that can be used to capture the instantaneous position of the encoder when an unexpected event occurs. When the LTC signal (rising or falling edge optional) is triggered, the hardware immediately stores the current count value in the latch register, which can be read by software for measuring event intervals or calculating speed. This is very useful when measuring the precise coordinates of an object passing through a sensor.

Software support and TriggerMaster tool

6.1 Operating System and Development Environment

Supports Windows 7/8.1 and RTX real-time extensions (8.1a/2009) to meet hard real-time requirements.

Provide sample programs and source code for VB/VC+/BCB for easy and fast integration.

It is recommended to use the TriggerMaster application, which provides a graphical interface for parameter configuration, trigger mode testing, and I/O status monitoring, greatly simplifying the debugging process.

6.2 Basic Configuration Process

Install the driver (download from the card CD or official website).

Run TriggerMaster to identify the card (multiple cards can be distinguished by the index switch on the card).

Select the channel, set the encoder input mode (A/B × 4, CW/CCW, etc.) and counting direction.

Configure comparator: Select trigger mode (linear/tabular/manual), set comparison point value or import point file.

Set the trigger pulse width and output polarity.

Enable output channel, observe oscilloscope or trigger device response.

Wiring guidance and anti-interference measures

7.1 Differential Encoder Wiring

Use twisted pair shielded wires to pair EA+/EA -, EB+/EB -, EZ+/EZ - respectively, and ground the shielding layer at one end (to control card DGND or chassis ground).

If the encoder has a single ended output (such as NPN open set), the negative terminal should be connected to DGND, and attention should be paid to voltage matching (5V or 24V current limiting resistors should be added).

7.2 Optical isolation output wiring

The open collector electrode output (TRG) requires an external power supply (VEXT) and a pull-up resistor. For example, to drive a 24V relay, connect OUTCOM to VEXT -, TRG to one end of the relay coil, and the other end of the coil to VEXT+, while also connecting a current diode (cathode to VEXT+).

The maximum load current is limited by the external power supply and internal optocoupler, and it is recommended not to exceed 50mA (please refer to the complete electrical specifications for details).

7.3 Power supply precautions

The card requires a PCIe slot to provide+5V (900mA), and an external+5V (500mA) supply for open collector electrode output and isolation side logic. Make sure the external power supply is stable and has low ripple.

Common troubleshooting and solutions

8.1 Unstable or jumping encoder readings

Check if the polarity of the wiring is reversed (swapping EA+and EA - will result in opposite counting directions and may cause garbled characters).

Confirm that the encoder power supply (usually 5V or 24V) matches the card. If the encoder output is differential, differential receiving mode must be used; If it is single ended, the negative terminal needs to be grounded and the input threshold needs to be adjusted (software selection).

Check if the shielding wire is well grounded. It is strongly recommended to use star grounding at the encoder end to avoid ground loops.

Reduce the count multiplier (e.g. from 4x to 2x) to test whether signal distortion is caused by high frequency.

8.2 Trigger output without signal

Measure the TTL-OUT pin with an oscilloscope to confirm that the software has enabled output and the triggering conditions have been met (such as the comparison value not being reached or the FIFO being empty).

Check if the trigger pulse width is set properly (too narrow may not drive the optocoupler).

For open electrode output, confirm that the pull-up resistor and external power supply are connected correctly, and whether the load is short circuited.