Xylem System 5000 User Manual - Manual (Page 41)

Inputs
39
Modbus Slave (Input)
Modbus Slave Input enables the System
5000
™
to act as a Modbus Slave on
a Modbus network. The Input reads
from the designated internal register
and uses the register’s value as the
Task value, retrieving the latest value
on each scan. The designated register
should be written to from an external
Modbus Master. The most recent value
is shown in the bottom left of the screen.
Retrieved values can be modified using
the Math & Data Options.
More information regarding Modbus
can be found in Chapter 8 of this manual.
SDI-12 Sensor
The SDI-12 Sensor Input allows
measurement parameters to be
retrieved from standard SDI-12
compatible sensors. Two SDI-12 Ports
are located on the upper block of the
front panel for ease of connecting
multiple SDI-12 sensors. Standard SDI-
12 sensors have a minimum of three
wires: +12V, Data, and Gnd.
The SDI-12 Sensor Input allows the
System 5000
™
to communicate with and
retrieve measurement parameters from
a standard SDI-12 sensor. The options
on the screen combine to
retrieve the requested data. For example, in the above screen, a command of “0M” would first be
sent, the reply would be received and parsed, the necessary time would be delayed and then the
data values would be retrieved. In this case, the first sdi 12 parameter would be recorded. Due to the
possible long length of time needed for SDI-12 Measurements, the SDI-12 Value can be manually
retrieved via the Test button and does not continuously retrieve the data. Once a Test has been
started the measurement can be aborted by pressing the Abort button, which is shown once the Test
has begun.
Sensor Address
Defines the sensor address to query. Addresses can be any single digit number or letter.
Sensor addresses are case-sensitive, thus sensor H is different from sensor h. Most sensors
typically use a number for their address. Finding unknown sensor addresses as well as
changing current addresses can be done within the SDI-12 Transparent Mode.