ADLINK LPCIe-8124-C Encoder Card Trigger Configuration Guide

ADLINK LPCIe-8124-C Encoder Card Trigger Configuration and Debugging Guide

ADLINK LPCIe-8124-C is a high-performance four channel encoder and high-speed trigger output card based on PCIe bus, designed for industrial automation scenarios that require precise positioning and synchronous triggering, such as automatic optical inspection AOI, distance measurement, motion control feedback, etc. This card supports up to four 32-bit orthogonal encoder inputs (compatible with A/B phase, CW/CCW, OUT/DIR formats, etc.), with a maximum input frequency of 18 MHz (4x multiplier mode), and is equipped with 14 built-in 32-bit comparators, which can flexibly configure multiple position comparison trigger modes such as manual, linear, table, and timing. The trigger output frequency is up to 4.4 MHz, and it provides three output interfaces: TTL, 5-24V open collector, and differential, suitable for various actuators.

Product positioning and core application scenarios

LPCIe-8124-C plays the role of a "position synchronization trigger" in the system. It reads the position value feedback from the encoder in real time, matches it with the preset comparison point, and once it reaches the specified position, immediately generates precise trigger pulses for triggering camera capture, light source flicker, laser marking, or actuator action. Compared to solutions that rely on software polling or CPU interrupts, hardware level triggering can ensure microsecond level response certainty and is a key component of high-speed and high-precision detection equipment.

Typical applications:

AOI detection: When the stage moves to a specific coordinate, it triggers a high-resolution camera to capture PCB solder joints or components.

Distance/angle measurement: Based on the encoder pulse count, trigger sampling at equidistant positions to construct contour data.

Flying needle test: precise control of probe contact timing.

Printing/Packaging: Achieving equidistant marking or cutting on continuously moving materials.

Hardware Overview and Interface Description

2.1 Main Technical Parameters

Project specifications

Number of channels: 4 encoder inputs+4 trigger outputs

Encoder input frequency up to 18 MHz (4 × A/B phase mode)

Trigger output frequency up to 4.4 MHz

The trigger pulse width can be programmed from 0.1 μ s to 3.2765 ms

Counter bit count 32 (encoder count)

14 comparators per channel (32-bit)

FIFO 1023 points/channel (used for pre stored comparison points in table mode)

Digital I/O per channel: EA+/-, EB+/-, EZ+/-, LTC (latch input), TRG (trigger output)

Isolation characteristics: Partial I/O optical isolation, isolation voltage of 2500 VRMS

Interface 50 pin SCSI-II connector

Power supply slot+5V/900mA, external+5V/500mA (for output)

Working temperature 0~50 ° C

2.2 Definition of connector pins (50 pin SCSI-II)

Encoder signal: EAx+, EAx -; EBx+, EBx-； EZx+, EZx-（x=1~4）， Differential or single ended input.

Position latch input: LTC1~LTC4 (optically isolated, with common terminal INCOM).

Trigger outputs: TRG1~TRG4 (optically isolated collector with OUTCOM common terminal), as well as TTL-OUT1~4 and TTL-IN1~4 (non isolated TTL level).

Power supply: DGND (Digital Ground), external power input for open collector electrode output.

Pin allocation is detailed in the table on page 3 of the manual. When wiring, it is important to pay attention to the polarity of differential signals (+/- pairing) and the voltage range of isolated terminals.

Encoder input configuration and counting mode

3.1 Input Interface Type Selection

LPCIe-8124-C supports three encoder signal formats, which can be configured through software:

A/B phase (orthogonal): A standard incremental encoder that supports 1 ×, 2 ×, and 4 × harmonics (the highest frequency at 4 × is 18 MHz, which means that when the encoder itself has a frequency of 4.5 MHz, it reaches a counting resolution of 18 MHz after 4 harmonics).

CW/CCW: Forward/Reverse Pulse, suitable for certain absolute values or stepper motor drive feedback.

OUT/DIR: Pulse+direction, commonly used in servo drive outputs.

3.2 Counting and comparator mechanism

Each channel has an independent 32-bit up/down counter that tracks position in real-time.

Built in 14 32-bit comparison registers, multiple comparison positions can be set simultaneously. When the count value matches any comparison value, the hardware automatically triggers the corresponding output action.

FIFO (1023 points) is used for "table mode", where users can pre install a series of comparison positions, and the cards will be matched one by one in order, suitable for continuous triggering with equal or non-uniform intervals.

3.3 Index (EZ) Signal and Reset

The encoder index (Z-phase) can be used to reset the counter or set a preset value, achieving absolute origin reference. It can be configured to automatically reset the counter every time the Z signal arrives, or triggered through software instructions.

Trigger output mode and pulse parameters

4.1 Trigger Output Type

TTL output (TTL OUTx): Standard 5V level, suitable for connecting camera trigger inputs or high-speed counters.

Open collector electrode output (TRGx): can be connected with an external pull-up resistor up to 5-24V, driving relays, solenoid valves or PLC inputs, with optical isolation and strong anti-interference ability.

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.

Confirm that the output polarity setting is correct (active high or active low).

8.3 Comparison of Trigger Position Deviation

Check if the initial value of the counter is correct (whether it was reset or pre-set before startup).

Confirm that the encoder resolution is consistent with the comparison point unit (for example, if the comparison value is in pulses, and the encoder has 1000 lines per revolution, then each revolution corresponds to 4000 counting pulses (4 x), and the comparison point needs to be calculated based on this).

Check if the FIFO is fully loaded in table mode, and if the number of comparison points exceeds 1023, load them in batches.

8.4 The board cannot be recognized

Check if the PCIe slot is working properly and try replacing the slot.

Check if the card index switch on the card is set correctly, and avoid conflicts if there are multiple cards.

Install the latest driver and check for unrecognized devices in Device Manager, manually update the driver path.

8.5 LTC latch value abnormal

Confirm whether the LTC signal level meets the input specifications (optically isolated input requires external power drive, non isolated TTL-IN can be directly connected to 5V).

Check if the latch trigger edge (up/down) matches the external signal.

Ensure that the counter counts properly before the latch occurs.

Suggestions for maintenance and long-term stability

Regularly clean the gold fingers and connectors to prevent poor oxidation contact.

Avoid hot swapping (although PCIe supports it, it is recommended to shut down and plug in to prevent surges).

If the working environment of the equipment is dusty, a dust cover can be used to protect the card.

Regularly backup the TriggerMaster configuration file (. cfg) for quick recovery of multi card batch deployment.