Teledyne t320u Manuale Utente

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Teledyne API – Model T300/T300M CO Analyzer 

130 

5.9.3.7. MANUAL ADJUSTMENT OF CURRENT LOOP OUTPUT SPAN AND OFFSET  

A current loop option may be purchased for the A1, A2 and A3 analog outputs of the 
analyzer.  This option places circuitry in series with the output of the D-to-A converter 
on the motherboard that changes the normal DC voltage output to a 0-20 milliamp signal 
(see Section 3.3.1.4).   

  The outputs can be ordered scaled to any set of limits within that 0-20 mA range, 

however most current loop applications call for either 0-20 mA or 4-20 mA range 
spans.   

  All current loop outputs have a +5% over range.  Ranges whose lower limit is set 

above 1 mA also have a –5% under range. 

To switch an analog output from voltage to current loop, follow the instructions in 
Section 5.9.3.1 (select CURR from the list of options on the “Output Range” menu). 

Adjusting the signal zero and span levels of the current loop output is done by raising or 
lowering the voltage output of the D-to-A converter circuitry on the analyzer’s 
motherboard.  This raises or lowers the signal level produced by the current loop option 
circuitry. 

The software allows this adjustment to be made in 100, 10 or 1 count increments.  Since 
the exact amount by which the current signal is changed per D-to-A count varies from 
output-to-output and instrument-to-instrument, you will need to measure the change in 
the signal levels with a separate, current meter placed in series with the output circuit.  
See Figure 3-9 for pin assignments and diagram of the analog output connector. 

 

 

 

06864B DCN6314