TURTLE
TOUGH
®
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Can I connect the output from TT-MA transmitter to non-isolated 4-20mA analogue inputs on my PLC?
No. The output from the TT-MA MUST ALWAYS be connected to isolated analogue inputs. If your PLC does not have isolated
analogue inputs, then you must add an isolator for each current loop to be used. The ground cannot be shared on both the analogue
current output from the TT-MA (which it is since it is a 3-wire device) and on the analogue input on the PLC. The ground for each
analogue input on the PLC must then always be isolated.
If I purchased a TT-MA-REL alarm/relay controller together with any of the measurement modules such as the TT-MA-pH,
TT-MA-ISE, TTMA-DO or TT-MA-CON can I modify the 4-20mA output scaling set by Turtle Tough?
Yes. The output scaling for each module can be modified within the prescribed limits in the documentation. If you modify the output
scaling from defaults for the TT-MA-pH, TT-MA-ISE, TT-MA-DO or TT-MA-CON modules you also need to modify the 4-20mA in
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put scaling for the TT-MA-REL and/or TT-MA-TOT module accordingly. The 4-20mA output can be used for both connecting to the
TT-MA-REL and/or the TT-MA-TOT pH compensation module as well as to other data acquisition or control devices using the bridge
type wiring configuration. If you ordered your system with both a measurement module and REL controller at the time of purchase
from the factory, your system will be wired as shown on the above wiring schematic.
To ensure optimal agreement between the measurement module (pH, ORP, ISE, Conductivity or Dissolved Oxygen) and the REL or
TOT module to which the analogue current loop output may be bridged, it may be necessary to refine the trim calibrations. In this case
it is recommended to perform the 4-20mA trim calibrations on the measurement module first with calibrated multimeter (see TT-MA
transmitter documentation for the setup parameters to be adjusted). The 4-20mA trim calibration for the REL or TOT modules should
be performed after the output trim calibrations have been refined on the measurement modules. When the trim calibrations are well
paired, the reading should match closely. Scaling the outputs more narrowly can make
matching the values easier.
What does the 4mA +/- X.XX% and 20mA +/- X.XX% label on the TT-MA transmitter mean?
Prior to dispatch each TT-MA transmitter has the 4mA trim offset and 20mA trim gain calibrated for optimal analogue precision. These
values may change slightly over time or due to environmental conditions. In such cases the analogue trim can be further adjusted
by modifying the appropriate parameter on the transmitter for the analogue output or analogue input of interest (see the relevant
instructions in the manual for that particular transmitter). If the TT-MA transmitter is reset in the field, the analogue 4mA trim offset
and 20mA trim gain calibration values shown on this label will be restored from the factory calibration and any modifications to this
calibration made after dispatch from the factory will be lost.
Why is there a serial number for each transmitter? I ordered a complete dual or triple transmitter or controller assembly. Shouldn’t
there be just one serial number?
Well actually not for how the modular and highly configurable TT-MA system works. Each measurement module (TT-MA-pH,
TT-MA-ISE, TT-MA-DO & TT-MA-CON) or complementary module (TT-MA-REL, TT-MA-TOT & TT-MA-DAT) will have its
own serial number. The complete assembly will be fabricated, prewired and calibrated as your have requested at Turtle Tough
but each individual component will have its own unique traceable serial number. Unlike many other electrochemical measure
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ment and control systems, component can be changed out, repaired or upgraded module by module and so our scheme (must)
separately tracks each transmitter module. Accordingly, removing or modifying the TT-MA serial number will void your warranty on
that particular module/transmitter. If no serial number exists on a unit or a label indicating “
DEMO ONLY
” exists on the transmitter
then assistance will be provided on a best faith basis but no specific warranty will apply.
What is the sampling rate of each of the measurement modules? Is there any time averaging for the view measurement during
calibration and measure modes? Can any of these settings be modified in the field?
The sampling rate for all of the measurement module is 4 Hz (4 data samples processed per second). There is time averaging (a.k.a.
dampener) implemented as most appropriate for that measurement type for both calibrate and measurement modes. The time
averaging can be disabled by special order units when it is desirable to measure the raw 4 Hz measurement data sample rate. In most
cases, a reasonable time averaging dampener yields the best results for calibration and control purposes. The time averaging settings
(in terms of the number of seconds used) is set at the factory and cannot be modified in the field. Please inquire to the factory prior to
purchase regarding any questions related to the dampener settings of your TT-MA module since they can often be optimized for your
use upon request at no additional charge but cannot be modified after dispatch to your location. For special applications, it is possible
for Turtle Tough to supply custom configuration of the TT-MA transmitters without any dampener applied at all to see real time data
at very high sampling frequency. This can be helpful for smaller pilot scale of benchtop use where these parameters can be change
quite quickly as compared to larger production size systems.
Is there any good reason to modify the analogue output scaling from the default values for the TT-MA-pH, TT-MA-ISE and
