HollySys LK Series User Manual

Chapter 7 IO Module
244 Beijing HollySys Intelligent Technologies Co., Ltd. All Rights Reserved
7.7 LK441 8-channel Thermocouple
Analog Input Module
7.7.1 Basic Features
 8-channel thermocouple or millivolt input
 Thermocouple type: B, E, J, K, R, S, T, N, C
 Range of millivolt signals: -12~32mV/-12~78mV
 Directly reported temperature value of a thermocouple signal type
 RTD cold junction temperature compensation
 Over-limit alarm
 Over range alarm
 Open wire alarm
 Isolation between the system and the field
 Field calibration
 Hot swapping
7.7.2 Operating Principle
The 24 VDC system power supply of the LK441 module supplies the power to the interface circuit by
outputting 2.5 VDC via isolated DC/DC. An opto-isolator is between the interface circuit and the
system, realizing the electrical isolation between the system and the field channel. The field signal is
converted into a digital signal via an A/D converter. Via optoelectronic isolation, it is read by the
microprocessor in the module, then uploaded to the CPU module via the PROFIBUS-DP bus.
DC/DC
Isolation converter
A/D
converter
Photoelectric
isolation
Microprocessor
Backboard
DC/DC
24VDC
Control
Input data
Field
Systerm
CH1
CH2
CH3
CH4
See channel
interface diagram
A/D
converter
CH5
CH6
CH7
CH8
Configuration data
Figure 7-46 Internal Structure Block Diagram of LK441

HollySys LK Series Specifications

General

Brand	HollySys
Model	LK Series
Category	Controller
Language	English