NI EPM high-performance DAQ cable

5. Analog and digital partitioning

The analog and digital lines are separated into two independent bundles by physical separation inside the cable, further preventing digital noise from entering the analog path through spatial coupling.

6.+5V power cord

Using 26 AWG thick conductors, much thicker than the 30 AWG of signal wires. This reduces the DC resistance during long-distance transmission, ensuring stable+5V voltage supply for DAQ devices, especially when supplying power to external sensors.

7. Overall shielding layer

In addition to all the internal structures mentioned above, cover with a layer of tin coated copper braided shielding mesh. This woven layer has high optical coverage (usually>85%) and provides good low-frequency magnetic field shielding effect.

8. Outer sheath

XPbT material (cross-linked polyolefin) has excellent mechanical strength and chemical resistance, and meets RoHS environmental requirements.

Comparison with other 68 pin NI cables

NI offers a variety of 68 pin cables to meet different cost and performance requirements. Understanding their differences can help in making the correct selection.

Cable model, shielding structure, typical use, applicable equipment

SHC68-68-EPM enhanced performance: analog/digital partition, individually shielded twisted pair for analog input, overall braided shielding, high-precision, low-noise measurement for M-series DAQCard、 Partial S series

SHC68-68 basic shielding: twisted pair cable, but without analog/digital partition, no separate shielding, cost sensitive, and low noise requirements M-series (connector 1 optional)

RC68-68 flat ribbon cable, unshielded, lowest cost prototype development, OEM integrated M series, E series

SH68-68-EP shielded, but without VHDCI connector, both ends are D-type 68 pin female E series, S series, B series devices with 68 pin quality end connected to USB M series, etc

SHC68-68-RMIO/- RDIO is similar to EPM and is designed specifically for the MIO/DIO connector of the R series intelligent DAQ. The R series FPGA devices NI 783xR, 781xR

SHC68U-68-EP has a reverse VHDCI male connector on one end, used for adjacent slots of DAQCard compact PCMCIA dual card configuration E-series DAQCard

Key difference: SHC68-68-EPM is currently one of the models with the strongest noise suppression capability among NI 68 pin cables, making it particularly suitable for use in multi-channel, high-resolution measurement systems. If there are high-power digital signals or switching power supplies in the system, EPM cables can significantly improve measurement accuracy.

Compatibility of accessories and application scenarios

The other end (68 pin female head) of SHC68-68-EPM can be connected to various NI and third-party accessories to achieve signal conversion, conditioning, or expansion.

1. SCB-68 shielded junction box

Provide 68 screw terminals that can be directly connected to on-site signals.

Built in cold junction compensation temperature sensor, suitable for thermocouple measurement.

Large area grounding plane and shielding shell, combined with EPM cable to form a complete shielding link.

2. SCC-68 portable signal conditioning carrier board

Up to 4 SCC signal conditioning modules (such as isolation, amplification, filtering, etc.) can be inserted.

Small footprint, suitable for desktop or portable systems.

3. BNC-2110 / BNC-2111 / BNC-2120 / BNC-2090

Transfer the DAQ signal to a BNC coaxial connector for easy connection to standard test lines.

Suitable for direct connection of high-frequency or high-voltage signals.

4. TBX-68 DIN rail junction box

Industrial grade installation method, suitable for wiring inside cabinets.

5. CB-68LP/CB-68LPR low-cost junction box

Economical solution, suitable for OEM or teaching experiments.

Special configuration:

When a 50 pin accessory needs to be connected, the 68M-50F-MIO adapter (mentioned in the document) can be used to convert the SHC68-68-EPM to a 50 pin interface.

For USB M-series quality termination modules (such as USB-6251), SH68-68-EP cable should be used instead of SHC68-68-EPM, as the latter has VHDCI connectors that do not match.

Cable selection rules for multi connector devices

M-series DAQ devices (such as NI 6225, 6255) typically have two 68 pin connectors (Connector 0 and Connector 1). The document provides clear recommendations:

Connector 0 (primary analog I/O): Use SHC68-68-EPM for optimal analog performance.

Connector 1 (auxiliary digital/timed I/O): Use SHC68-68 (low-cost shielded cable) because the signal on this connector is less sensitive to noise.

For DAQCard (PCMCIA card), when two cards are inserted adjacent to each other into the slot of a laptop, due to space limitations, the standard VHDCI connector may not be able to be inserted side by side. At this point, the SHC68U-68-EP cable should be used, with its connector direction reversed to enable and arrange the wires.

Overview of other related cables and accessories

Although this article focuses on SHC68-68-EPM, NI provides a complete cable accessory ecosystem covering various pin numbers, briefly introduced as follows:

100 needle device

SH100100: 100 needles to 100 needles, used for E-series 100 needle equipment.