INTRODUCTION
The SEM210
is a second generation 'Smart' in head temperature transmitter that
accepts any commonly used temperature sensor, Slidewire transducer or
Millivolt signal and converts the output to the industry standard 4 to
20 mA transmission signal.
The sensor type and range are easily
programmed using a PC and a simple Windows™ based software program.
Connection from the PC serial port is made using the same wires that
carry the 4-20 mA output signal. This simplifies connection and
allows for re-programming or interrogation of the SEM210
while it is installed in the loop. Sensors can be
changed without the need for re-calibration.
Isolation is a standard feature,
removing all ground loop effects as the input is electrically and
physically isolated from the loop power supply. The use of two
micro-processors results in error-free data transmission across the
isolation barrier.
The very small size coupled with the
versatility of this universal transmitter make it the ideal choice for
every temperature measurement application, resulting in lower
inventory, greater operational flexibility and, in common with our
other products, a low cost of ownership.
INPUTS
Pt100 Platinum resistance sensors,
Thermocouples, Millivolts or Slidewire sensors may be connected to the
unit. The Type "X" option allows for custom sensor
characterization. This option is factory pre-configured to customer
specifications.
The Process Variable may be filtered to remove
incoming signal noise using one of four settings. If the
‘Adaptive’ function is selected the filter continuously adjusts to
the incoming signal to noise ratio in order to choose an appropriate
level of filtering. In this way a slowly changing input can be heavily
filtered but if the signal goes through a sudden change the filter
quickly reduces allowing a rapid response, other settings are; off, 2
seconds, 10 seconds.
A user programmable offset is
available to remove any system errors that may be present and sensor
referencing enables the transmitter to be accurately matched to a
particular sensor.
CURRENT OUTPUT
In normal operation the current output
varies between 4 and 20 mA. If the input sensor develops a fault, or
the software in either of the two microprocessors detects an error,
then the current output is driven either upscale (greater the 20 mA)
or downscale (less than 4 mA) depending upon the sense of the burnout
parameter selected.
COMMS OPERATION
The transmitter is accessed via the comms
interface adapter for re-programming or examination of the process
variable and status information. The interface adapter converts the
special communications signals on the transmitter power connection
cables to the standard RS232 in order to connect directly to a PC
serial port. There are two methods of connecting the interface adapter
to the transmitter (1) using the adapter’s own power supply or, (2)
using the power from an existing loop.
