Future Design MCT-CM, User Manual

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MCT-CM
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Choose which loop value is to be retransmitted for the loop by pressing the appropriate function select button;
PV, SP or %Out. If ‘None’ is selected, the output will remain in the off state, i.e., 0Vdc or 4mA depending upon
the output type selection.
Enter the minimum and maximum values for which the output is to retransmit. The output range is -32760 to
32760 for a decimal point resolution of zero, -3276.0 to 3276.0 for a decimal point of one, -327.60 to 327.60 for
a decimal point of two and -32.760 to 32.760 for a decimal point resolution of three.
Once all settings have been made, press the ‘Save’ button to save the changes. If you do not press the ‘Save’
button, all changes will be lost if you leave the screen or navigate to another analog output.
10.6.1 Retransmitting Loop Percentage of Output
Depending upon the loop control being used, the percentage of output value for bimodal control (heat/cool) is
represented differently. For example, FDC 100 and 300 series controls represent heat output as a value from
0% to 100% while the cool output is represented as a value from 0% to -100%. Other controls supported by
the MCT may split the standard 0% to 100% range and use 50% to 100% for heating and 50% to 0% for cooling.
If the analog output is being used to control the position of a cooling valve or SCR power controller of a heater
bank for example, it is important that the analog output supply only the signal for the proper heating or cooling
range in order to properly control the amount of cooling or heating applied to a process.
The MCT provides the ability to supply only the heating output, cooling output or a combination of heating and
cooling outputs from its analog outputs. For example, if an FDC 300 series control is used, setting an
‘Out Min’
to ‘Out Max’ range of 0% to 100% will result in an analog output of 0-10Vdc or 4-20mA for an output of 0% to
100% heating. If a different model of controller is used that represents heating as 50% to 100% with cooling
from 50% to 0%, setting an
‘Out Min’ to ‘Out Max’ range of 50% to 100% will result in an analog output of 0-
10Vdc or 4-20mA for an output of 0% to 100% of the heat output.
In order to retransmit a cooling percentage of output, the MCT allows the analog output range to be inverted
relative to the value representing the cooling percentage of output. This allows the positioner of a cooling valve
for example, to receive a 0-10Vdc or 4-20mA signal representing 0% (full closed) to 100% (full open) of cooling
even if the cooling percentage represented by the controller is 50% (no cooling output) to 0% (full cooling
output).
For example, if 0% to -100% represents no cooling to full cooling, setting the
‘Out Min’ field to 0% and the ‘Out
Max’ field to -100% will produce an analog output of 0-10Vdc or 4-20mA for an output of 0% to 100% cooling.
If a model of controller is used that represents cooling as 50% to 0% while heating is represented as 50% to
100%, setting an
‘Out Min’ to ‘Out Max’ range of 50% to 0% will result in an analog output of 0-10Vdc or 4-
20mA for an output of 0% to 100% of the cool output.