140 of 220 Digital Inputs & Outputs - Anatel A643a
RPS - June 2007 - Edition 12
Operator Manual Anatel
10.2 Digital Inputs
Both of the digital inputs perform specific Anatel A643a functions, allowing total control over its
operation as well as synchronization with the rest of the process. The first set of inputs is used
to initiate an analysis from an external device. The analysis is based on the instrument’s
specified Sample Time and Cycle Time settings. The second input dictates the instrument’s
operational mode as either Auto TOC or Purge. Both inputs also require that the Analyzer be
placed under Digital Control.
10.2.1 Hardware Setup
The two digital inputs share a common positive terminal. They are driven by a 5 to 30 VDC
external power source or the Analyzer’s 12 VDC, 0.5 Amp Bias and designed to operate from
open collector, open drain or relay outputs. Each input draws between 1 and 14 mA, depending
on the applied voltage. The hardware connections are established as described in “General
Information” on page 139, the Inputs terminals having the following designations and functions:
IN1* Allows external initiation of an analysis. When Input #2 selects the Auto TOC Mode, a
high-to-low state transition forces the instrument to initiate an analysis cycle.
IN2* Selects between the Auto TOC (high state) and the Purge (low state) Mode. State
transitions are ignored on IN1* when the instrument is in the Purge Mode.
Table 10-1 : Digital Inputs
IN1* IN2* Mode
X High Auto TOC
X Low Purge
H
→L† High Begin Analysis
†Min 0.1 second pulse duration
X = Don’t care
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