Page 25
Installation
Discrete inputs
The analyzer has two discrete inputs, referred to as Digital Input 1 and Digital Input 2.
Wiring connects to terminals on connector block J24, as listed in Table 4. Both inputs are
optically isolated. The inputs are rated for 5 - 30VDC, 2 - 15mA. Terminals 4 and 5 of the
discrete input terminal provides a 12 VDC output that can be used to drive each digital
input. Both Digital input 1 and input 2 share a common positive power connection.
The default state for each input is a high state (no voltage applied across the input). High
state is defined as no power applied across the input terminals. Low state is defined as
power applied across the input terminals.
• Digital input 1 initiates a TOC analysis. When power is applied across pins 1 and 2
the analyzer input is changed from a high to low state. (When power is applied the
optical input LED is powered and the input is activated.) An input trigger of at least 500
mSec (0.5 seconds) is required. When a high to low trigger is detected on the input
the analyzer stops the current operation and runs a single TOC analysis. When the
analysis is complete, the analyzer returns to the mode defined by digital input 2.
During the TOC analysis, the analyzer ignores all subsequent triggers.
• Digital input 2 controls the analyzer run mode. If digital input 2 is not powered
(High state) the analyzer is in TOC mode. If power is applied across pins 1 and 3 the
analyzer input is changed from high to low and the analyzer will run in flow with
conductivity mode.
The control required to activate digital inputs 1 and 2 can be configured by the user. For
example, Digital Input 1 can be configured to trigger from the default change from high to
low state or inverted to trigger from a change from low to high state. Refer to TOC,
page 56 for instructions on inverting the operation of Digital Input 1 or Digital Input 2.
Table 4
J24 connector block: Discrete input wiring terminal designations
J24 Block Terminal Description Variable Designation
1 Common connection for external sourcing (+) Common DI1/2+
2 Digital input 1 voltage source return input (–) Initiates TOC analysis DI1–
3 Digital input 2 voltage source return input (–) Analyzer mode DI2–
4
• 12 VDC power supply +
• Connect only if output device requires power
supply
Output power supply +12V
5
• 12 VDC power supply –
• Connect only if output device requires power
supply
Output power supply GND
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