EPI and CPI networks

GRANITE 9 and GRANITE 10 data loggers support EPI networks. EPI is the preferred Spectrum-to-data logger connection due to multi-module support, superior time synchronization between modules (with a precision of 50 ns compared to 100 μs for EPI vs CPI, respectively), and higher data transfer rates than those achievable with a CPI network.

Data loggers such as the GRANITE6, CR6, or CR1000X do not support EPI, but can connect to a Spectrum using their CPI bus. A CPI network works well for slower measurements (less than 1,000 Hz) with a single Spectrum module.

NOTE:

       When a Spectrum is on a CPI network, no other CPI devices can be present.

EPI basics

  • GRANITE 9 and GRANITE 10 data loggers support one EPI network with two EPI ports

  • EPI networks offer 100 times greater throughput than CPI networks

  • Module-to-module synchronization is on the order of 1000 times better compared to CPI synchronization (100 ns for EPI vs. 100 μs for CPI)

  • In a EPI network, devices are daisy-chained with a 100-meter (328 feet) cable limit between devices

  • Each Spectrum features two EPI ports for signal reception and renewal, facilitating network expansion by up to 100 meters between modules

  • A maximum of 10 EPI modules can be connected in a single EPI network

  • When using multiple Spectrums on an EPI network, assign a unique EPI address (1-120) to each module

  • Monitor EPI network capacity in the host data loggers CPIStatus and EPIStatus tables

CAUTION:

A CPI terminator should never be used in an EPI network.

CPI basics

  • Only one Spectrum can be on a CPI network

  • A CPI terminator may improve network performance

  • The CPI network speed can be optimized for data speed or cable distance

  • The CPI Calculator (a downloadable Excel file from the Spectrum web page on the Campbell Scientific web site ) can help determine CPI network capacity

  • Monitor the CPI network capacity (percent) in the host data logger Status table