Spectrum Controls 1762sc-IF4OF4 - Manual (Page 10)

1-4 MicroLogix™ 1200 Analog Combo Module (4Ch IN / 4Ch Out)
User’s Manual Pub. 0300247-01 Rev. C
6 Flat ribbon cable with bus connector (female)
7 Terminal block
8 DIN rail latch
9 Pull loop
1.6.1 LED Indicator
The 1762 combo module uses a single green LED to show operational status of the
module. The status LED has the following blink codes:
Blink Code Description
Blinks rapid
green The module is not in run mode
Solid Green Startup has completed, all internal tests have passed and the module has
received a valid configuration from the PLC
Off Hardware error
Section 1.7
System
Overview
The module communicates to the controller through the bus interface. The module also
receives 5 and 24V dc power through the bus interface.
Note: An external power supply is required for all 2-wire input transmitters.
1.7.1 Module Power-up
At power-up, the module performs a check of its internal circuits, memory, and basic
functions. During this time, the module status LED is blinking rapid green. If no faults
are found during power-up diagnostics, the module status LED is turned on.
After power-up checks are complete, the module waits for valid channel configuration
data. If an invalid configuration is detected, the module will generate a PLC fault. Once
a channel is properly configured and enabled, it continuously converts the input or output
data to a value within the range selected for that channel.
Each time a channel is updated by the combo module, that data value is tested for an
open-circuit, short-circuit or “input/output data not valid” condition. If such a condition
is detected the channel data value will fail to a user defined state defined in the module
configuration settings. For more details, refer to Chapter 3.
Using the module’s input and output image table, the controller reads or writes the two’s
complement binary data to and from the module. This typically occurs at the end of the
program scan or when commanded by the control program. If the controller and the
module determine that the data transfer has been made without error, the data is used in
the control program.
1.7.2 Module Operation
Input Channels
When the module receives the input from an analog device, the module’s circuitry
multiplexes the input into an A/D converter. The converter reads the signal and converts
it as required for the type of input. If thermocouples are being utilized, the module