Dynasonics TFXM Series Ultrasonic Multi-Channel Flow Meter - Manual (Page 14)

Rev. 8/02 -1. 13- TFXM
Series TFXM contains integrated RS485 communications, one 4-
20 mA output per measurement channel and two SPDT relays per
measurement channel. Other auxiliary input/output options are
available. All outputs are 2,500 V optically isolated from TFXM
power and Earth grounds -- eliminating the potential for ground
loops and reducing the chance of severe damage in the event of
an electrical surge.
Auxiliary options that are available include: secondary 4-20 mA,
secondary dual-relay, rate pulse, RS232C, a 200,000-event
datalogger and BTU-Pro heat-delivered option. In order for an
Auxiliary output option to be operational, either the 4-20mA or the
dual-relays must be disabled for that measurement channel. All
outputs are field configurable by utilizing the keyboard or
ULTRALINK interface. Field wiring connections to the outputs are
made to the terminal blocks located within the wiring access
panel.
The two, three-position DIP -switches located within the wiring ac-
cess panel configure the TFXM for input/output options. The flow
meter is shipped from the Dynasonics factory with the options or-
dered configured and installed. Typically no adjustments to these
switches are necessary. The switch lever to the left in each DIP
switch block is utilized to configure the 4-20 mA output as either
internally or externally powered. The other two switches in each
DIP-switch block are used to disable either the 4-20 mA or dual-
relay output should an Auxiliary output be installed within the
TFXM enclosure.
The 4-20 mA Output interfaces with virtually all recording and
logging systems by transmitting an analog current signal that is
proportional to system flow rate. The output can be configured to
be either internally or externally powered by setting the left DIP -
switch at SW1 for Channel 1 and SW2 for Channel 2. Refer to the
Field Wiring Diagram at Figure 1.4 for terminal block and DIP -
switch locations.
When powered from internal power, the 4-20 mA output can pro-
vide loop current for a maximum of 800 ohms of total loop resis-
tance. When powered externally, the maximum load varies with
the level of the voltage source. The insertion loss of the 4-20 mA
circuit is 5Vdc, so the maximum loop load that can be powered is
calculated by the equation:
PART 1 - INPUT/OUTPUT CONFIGURATION
General
DIP-Switch
Configuration
4-20 mA
Output
Configuration