Hitachi NJI-350B - Manual (Page 13)

Chapter 1 Features
1-1
Chapter 1 Features
1. Multifunctional all-in-one type PLC
The MICRO-EH is a multifunctional all-in-one type PLC that contains all necessary parts—a power supply and
CPU parts as well as I/O units--within one unit.
Three sizes of PLCs are available: 10, 14, and 28 points. A type with 23 points plus three points of analog I/O
having the same size as the 28-point PLC is also available. Moreover, for PLCs with more than 14 points, it is
possible to install additional 14 or 28 point expansion units up to four units. Thus, the MICRO-EH can control a
wide range of systems from small to medium size.
2. Simplified positioning by counter inputs and pulse train outputs
The function of inputs/outputs can be selected from four modes. By selecting a mode, inputs/outputs that are used as
normal inputs/outputs can be set as counter inputs and pulse train outputs. Through a combination of these special
inputs/outputs, it is possible to control positioning without using special modules.
3. Simplified instrument system by analog integration
For the 23-point PLC, there are two points of analog input and one point of analog output for which both current
and voltage can be selected. High performance analog channels, with a resolution of 12 bits and an overall accuracy
of
±1 % or less, can be used without requiring special settings of the channels; thus, a simplified instrument system
can easily be implemented.
4. Superior upward compatibility
The MICRO-EH has been developed as a part of the EH/H series family.
Debugging and programming can be performed using the same concept as for the EH/H series.
In addition, the MICRO-EH software property can effectively be applied to the EH/H series for future system
expansion.
5. Easy maintenance through removable terminal blocks and installation on a DIN rail
All models of the MICRO-EH series support the DIN rail so that the PLC can easily be mounted and dismounted. In
addition, the I/O section of the 14-point PLC or more utilizes a removable terminal block. Thus, erroneous and
faulty wiring that may occur when connecting to external devices can be reduced.
6. Remote maintenance through modem connection
Communication with remote sites can be performed via dial-up line by connecting a modem to port 1 on the 14-
point PLC or more of the MICRO-EH series. It is possible to monitor and manage remote systems from an office or
monitor room.
7. Easily adjustable potentiometer
The 14-point PLC or more of the MICRO-EH series supports two potentiometers.
By using these potentiometers, it is possible to rewrite internal output values in real-time by one driver without using
peripheral devices. Since the resolution of the potentiometer is 10 bits, it is possible to set any value from 0 to 3FFH.
To obtain stable analog values of the potentiometers, it is possible to sample 1 to 40 analog values of the
potentiometers and average them.
8. Maintaining programs without a battery
It is possible to retain user programs in case of out-of battery or no battery, since FLASH memory is used as the
backup memory for the user programs. However, a battery is necessary for data memory backup. (See the Notes in
Chapter 7.1 for a list of precautionary details.)
9. Support for various programming languages
The MICRO-EH supports “Pro-H,” the programming software that allows creating programs in five programming
languages regulated in IEC1131-3. This means that customers who have learned languages other than Ladder can
easily create programs with this programming software.
10. Compliant with overseas specifications as standard
All types of MICRO-EH PLCs have obtained the CE mark, C-TICK and UL. Therefore, systems in which these
PLCs are installed can be exported without requiring any modification.