Hach 1950Plus, Инструкция по эксплуатации инструмента, Страница: 143 / 188

Section 8
Page 143
UVTOCTroubleshooting and Service.fm
Service Menus
8.6.5 Output Adjust
The procedure to change any of the
displayed values is identical for
Analog channels 1 and 2.
The Output adjust function allows calibration and checking of the two analog
channels. It also allows the output of a % scale for the selected output
channel by first selecting the channel and then selecting the zero, span, or
check option.
The analog outputs are line
powered and should not be
connected to a load with voltage
that is independently applied.
The output adjust menu is particularly useful to trim the analyzer’s output to
exactly match the input of a DCS system—allowing accurate repeating of
signalled values.
In order to accurately calibrate the analog outputs, the two analog circuits
must be connected to the circuit loop which operates analyzer for at least five
minutes before any adjustments are performed. This means that the loop
must not be broken (open-circuited) during the adjustment of zero and span
with the DCS loop load resistor is in place. If the jumper configuration is
changed recalibration may be required. For wiring details and jumper
configuration, see
section 2.4 on page 41 . For electrical parameters, see
Technical Specifications on page 13 .
1. To display the Output adjust screen, press the UP button while in the
Service menu.
2. Press ENTER. The CH1 (Analog channel 1) screen is displayed. To
display CH2 outputs, press the UP button. Press ENTER to select the
displayed channel.
The three options for each channel are Zero, Cal, and Cal check. (See the
complete descriptions of each option below.) Scroll through the options using
the UP and DOWN buttons. Press ENTER to select the option.
Channel 1 and 2 Zero
The value of 608 is the current zero digital count for the selected output
channel (CH1 in the screen above). Verify that 4 mA are measured on your
multimeter or that 0 is repeated on a DCS.
1. To adjust the reading, press ENTER.
2. Asterisks flash on either side of the displayed value. Use the UP and
DOWN buttons to ramp the value and the current (mA) up or down. The
count range for Zero is 0 to 1024 counts. The displayed count must equal
4 mA on your multimeter.
O u t p u t a d j u s t
C H 1
C H z e r o
608