Sutron Corporation 8310 & 7310 Users Manual 8800-1125Rev. 2.7 (BETA) 4/16/2014 pg. 161
When used to make frequency measurements, the 8310 counts the number of pulses it sees in a
user set period to determine the frequency. The minimum frequency depends on the period
selected. A period of 1 second can measure a minimum of 1 hz. A period of 500ms can measure
a period of 2 Hz. The maximum frequency is 8KHz.
Shaft Encoder (Quadrature) Sensors
The digital inputs are compatible with quadrature shaft encoders manufactured by Sutron and
others. A quadrature sensor is one that uses two signal wires to code 4 states. A quadrature
sensor connects to the same terminals that can be used for counter and frequency
measurements. When you select a quadrature sensor, the 8310 reprograms its input circuitry to
handle the input as a quadrature rather than a frequency. When selected for an encoder, you
cannot use the same terminals for frequency/counter inputs.
Quadrature sensors generally require 4 wires: +12 to sensor, GND, signal 1, signal 2. The
maximum speed supported by the 8310 is 4Khz. This equates to 40 revolutions per second (RPS)
on a 400 count/turn encoder or 160 RPS for a 100 count/turn encoder.
SDI sensors
SDI 12 is an interface standard for sensors. The intent of the SDI standard is to minimize the
difficulty of interfacing the different types of equipment available from different manufacturers,
to various data recorder manufacturers’ products. SDI allows you to connect up to 10 sensors
with as many as many as 9 parameters each. The interface is implemented using three wires:
ground, +12V and a bi directional data line. Examples of SDI sensors are shaft encoders,
pressure sensors, water quality monitors, and analog expansion modules. The list of SDI 12
sensors is growing all the time.
SDI sensors connect to the 8310 using the SDI-12 terminations G (Ground), + (12VDC) and D
(Data). On the 8310, there are two sets of SDI-12 connections for convenience. They are both
connected to the same SDI-12 port.
The 8310 protects the SDI +12V line with a thermal, self resetting fuse.
You do need to be careful how you schedule the SDI sensors to be read. Many SDI sensors take
a second or two to read; however, there are SDI sensors can take up to 180 seconds to read.
Keep in mind the performance of the sensor you are connecting to make sure you do not set the
8310 to measure it more frequently than it can. If you do select a schedule that is too fast for
the sensor, you could end up with data missing in the Log.
Hint: you may want to use the SDI C command to make a concurrent measurement of several
sensors to help improve performance.
Inputs and Input Connections
As you setup a measurement, you will be asked to define the type of the input and the
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