ANATEL A643, Operator'S Manual, Page: 121 / 222

Anatel A643a - Analog Outputs 121 of 220
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Anatel
Operator Manual
9 Analog Outputs
9.1
General Information
Anatel A643a Analyzers provide two methods for outputting signals to external analog devices.
The first offers TOC data through the dedicated 4–20 mA port located on the instrument’s
Connector Block; the second outputs conductivity (or resistivity) and/or temperature data to
optional External DAC (Digitalto-Analog Conversion) Modules via the Analyzer’s
DIAGNOSTICS port. The output from the DAC Module is a 4-20 or a 0-20 mA signal which then
can be used by a variety of compatible analog devices.
This section describes how to establish hardware connections for the standard TOC output and
the optional External DAC output as well as how to set the necessary operational parameters
for each.
9.2
TOC Output
As noted, an analog signal corresponding to the Analyzer’s TOC reading is always available via
its 4-20 mA port. This current output may be converted to a voltage if desired by inserting a
conversion resistor into the wiring scheme.
Software settings determine the analog output range in addition to its corresponding zero-scale
and fullscale values. A user-specified signal also may be output to designate Anatel A643a
Analyzer alarms.
9.2.1 Hardware Setup
The Analyzer can generate an isolated current output ranging from 4-20 or 0-20 mA that is
proportional to its most recent TOC reading. This analog output drives resistances between 50
and 500 ohms, including the interconnecting cables. The signal can be converted to a voltage
output by incorporating an appropriate conversion resistor:
Note that the precision of the resistor directly affects the accuracy of the data. A 1% wirewound
resistor or better is recommended. For maximum data integrity, the resistor should be mounted
across the receiving device’s input terminals.
TOC Analog output connections are made to the Analyzer’s I/O Connector Block as follows:
Table 9-1 :
Conversion Reistors
Resistor
4–20 mA
DC Voltage Range
0–20 mA
DC Voltage Range
50
Ω
0.2–1 VDC 0–1 VDC
250
Ω
1–5 VDC 0–5 VDC
500
Ω
2–10 VDC 0–10 VDC