How to Open and See What's Inside an HMI OP 320 Teardown

OP 320 HMI

is a monochrome graphic panel with 20 configurable keys. It's supposed manufacturer is XINJE Electric Co, but there is not a visual reference in the case nor in circuit boards. Its aspect is very similar to KINCO MD204L.

This HMI cost around 40 dollars (shipment included!), is powered by 24 V DC and have RS-232 and RS-422 communication interfaces, its programmed using the RS-232 port using a proprietary software. Have multiple industrial communication protocols. so is a very attractive solution to interface microcontroller based systems, because its integrated display, keyboard, control logic, using only a serial port, all encased in an "industrial like" case that the manufacturer claims to be IP65 for front panel.

Step 1: REQUIRED COMPONENTS

Here is the list for the required components for this project with the absolute lowest prices! If you find something cheaper somewhere, please msg me!

Low cost industrial HMI compatible with most PLC ( http://goo.gl/ncqgUr )
Plastic spudger or pry tool ( http://goo.gl/5XYq2H )
3mm Phillips screwdriver ( goo.gl/R88c3f )

Step 2: TEARDOWN PROCESS

TEARDOWN PROCESS

To open the OP 320 case a 2.4 mm x 40 mm Phillips screwdriver is required

First, remove 24V power terminal and release the 4 screws that holds the back case. Then pull the main board to disconnect from the display board, the boards are connected to a 20 pin single line connector.

Carefully disconnect the membrane keyboard connector (9 pin single line). This allows to totally disconnect the main board. The last step is to remove the spacer and the 3 screws that hold together the display board with the front panel.

Step 3: ELECTRONIC BOARDS AND MAIN COMPONENTS

MOST IMPORTANT SEMICONDUCTOR LIST IN MAIN BOARD

Part #: Description

Scratched info: Microcontroller, looking the package and pin arrangement, probably an MCS-51 compatible with onboard RAM and FLASH

LM2576S-5.0: SWITCHER 3A Step-Down Voltage Regulator

SP202EEN: Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers

74HC245D: octal transceiver featuring non-inverting 3-state bus compatible outputs in both send and receive directions7705ACintegrated-circuit supply-voltage supervisors

MAX 485: Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers