UniOP BKDR-16 human-machine interface

UniOP BKDR-16 Human Machine Interface: A Comprehensive Analysis from Technical Specifications to Engineering Practice

In industrial automation sites, human-machine interface (HMI) is the core bridge between operators and control systems. A stable, functionally clear, and easily integrated HMI often determines the debugging efficiency and operational reliability of the entire production line. The BKDR-16 model in the UniOP series, with its compact 5.6-inch monochrome LCD display, rich physical buttons, and multiple communication interfaces, occupies a place in multiple segmented industrial fields such as small complete sets of equipment, old production line renovation, and low-cost monitoring stations. Despite the comprehensive evolution of LCD display technology towards color and high resolution, the monochrome industrial grade HMI represented by BKDR-16 still retains unique value in strong light visibility, extreme temperature adaptability, and low-power scenarios. This article will deeply analyze the various parameters, functional logic, and typical applications of BKDR-16 from the perspective of engineering and technical personnel, and based on on-site experience, deduce its common failure modes and replacement upgrade paths, providing a practical technical reference for engineers who are currently using or planning to maintain the equipment.

Product positioning and overall architecture

BKDR-16 is a compact human-machine interface product in the UniOP family, with a clear design goal of providing complete process monitoring, alarm management, data recording, and network interaction capabilities with limited hardware resources. From the overall dimensions, the mechanical opening size of the equipment panel is approximately 195.00 mm × 147.00 mm (tolerance ± 0.50 mm), and the total size including the rear wiring terminals in the depth direction is controlled at around 205 mm. This external specification enables it to adapt to the installation windows of most standard industrial control cabinets, especially suitable for replacing old monochrome touch screens or text displays from brands such as Mitsubishi, Omron, or Delta.

In terms of power supply, BKDR-16 adopts the most mainstream 24V DC power supply in industrial sites, with a typical power consumption of less than 10W. It can be directly powered by the PLC's sensor power supply or independent switch power supply, without the need for additional 220V isolation transformers. This is extremely user-friendly for distributed I/O sites or mobile operation panels.

In terms of memory architecture, the device is equipped with a 512KB Flash EPROM onboard, of which 64KB is fixedly reserved for the communication protocol stack. The actual program storage space available to users is about 448KB, and it supports expansion up to 1MB. This capacity is sufficient to accommodate dozens of screens, thousands of alarm messages, and complex macro scripts in the era of text and graphics mixed interfaces. It should be noted that the program storage area and the recipe data area are independent of each other, and the recipe dedicated 16KB space uses non-volatile storage. Even if the main program is refreshed, the recipe parameters will not be lost - this feature is crucial in batch production equipment.

Display and Interaction: Advantages and Limitations of Physical Buttons

The BKDR-16 is equipped with a 5.6-inch monochrome LCD with a graphics resolution of 320 × 240 pixels. This resolution may seem low under current standards, but it is sufficient for displaying numbers, bar charts, trend curves, and status text in industrial settings. Monochrome display (usually yellow green background with black text or white background with gray scale) has an advantage that color screens cannot compare to: in strong sunlight or high brightness ambient light, the readability is much higher than that of ordinary TFT LCD. Many outdoor devices, such as hydraulic fracturing trucks, drilling rig control rooms, and port lifting equipment, still tend to choose monochrome or high brightness reflective screens, and BKDR-16 precisely meets such needs.

In terms of interaction, BKDR-16 does not use a touch screen, but provides a complete physical keyboard - a total of 37 keys, including 14 independent function keys and a complete numeric keypad. This design may seem "retro", but it actually has clear advantages in specific scenarios:

Clear operational feedback: The travel and tactile sensation of mechanical buttons can prevent accidental contact, especially suitable for situations where operators wear thick gloves (such as cold storage and casting workshops).

Function keys can be customized: 14 function keys can be assigned through engineering configuration software for screen jumping, bit setting, numerical input, or macro triggering, without relying on screen menu layer by layer switching.

High efficiency of numerical input: The independent numeric keyboard combined with the Shift key can quickly input set values, which is more in line with muscle memory operation logic than the virtual keyboard on the touch screen.

At the same time, 10 user programmable LED indicator lights are integrated on the front panel of the device. These LEDs can directly map the position status in the PLC (such as motor operation, valve opening in place, fault alarm), and can also serve as backlight for operation guidance. Compared to drawing an indicator light occupying the display area on the screen, physical LEDs have faster recognition speed and do not consume visual resources.

Detailed explanation of communication ports and network capabilities

The configuration of communication interfaces in BKDR-16 is considered rich among similar products, which is also an important reason why it can adapt to various PLC brands and old systems. Its ports are divided into the following parts:

PC/printer dedicated RS-232 port: used to connect to the upper computer for downloading projects, online debugging, or directly output alarms/data records to the serial port micro printer. This port uses a standard DB9 male header and supports a maximum baud rate of 115200 bps.

PLC communication port (multiple physical layer multiplexing):

The same physical interface can operate in RS-232, RS-485, or CL 20 mA current loop mode (suffix -0045) through dip switches or software configuration.

The RS-232 mode is suitable for point-to-point short distance connections (such as PPI ports with Siemens S7-200 and programming ports with Mitsubishi FX series).

RS-485 mode supports multi-point bus and can mount up to 32 nodes, suitable for Modbus RTU master station or communication with multiple frequency converters and instruments.

The 20 mA current loop is an extremely ancient industrial communication method (commonly found in European CNC systems and PLCs in the 1970s and 1980s, such as early Siemens S5, AEG, etc.). BKDR-16 retains this interface, which means it can directly replace old operation panels on production lines that are still running antique controllers without the need for expensive protocol converters.

Aux auxiliary port: This port is a special expansion interface in the UniOP product line that can be connected to an external keyboard, barcode scanner, or a second HMI as a mirror slave. During on-site debugging, engineers often use the Aux port to temporarily attach a debugging keyboard without the need for frequent plugging and unplugging of the main communication cable.

UniNET Network: BKDR-16 supports the UniNET protocol and can serve as both a SERVER (providing data to other UniOP panels) and a CLIENT (reading data from other panels or gateways). This feature makes it highly flexible in distributed monitoring scenarios - for example, in a large batching workshop, multiple BKDR-16s are installed on operation columns on different floors, forming a UniNET network through RS-485 bus. Any one can display key data of the entire system without the need to configure PLC communication for each device separately.

In depth analysis of software functions

The engineering configuration of BKDR-16 is completed through UniOP's dedicated Designer software (early versions were UniOP Workshop). Although the operating logic of this software differs from modern HMI software such as TIA Portal and GP Pro EX, its functional density is not inferior.

4.1 Alarm System

The device supports up to 1024 alarm messages, each alarm can be associated with a specific bit address (from PLC or internal flag), and can individually define the display text, priority, confirmation method, and historical record behavior when triggered. The alarm information page is automatically generated by the system, without the need for users to manually layout it one by one. When an alarm occurs, BKDR-16 can respond in one or more of the following ways:

Highlight on the alarm page;

Trigger buzzer (internal buzzer);

Flashing LED prompts through function keys;

Output alarm content to the printer.

The capacity of 1024 is sufficient to cover the abnormal monitoring of all key process points in a medium-sized workshop.

4.2 Variables and Visual Logic

There is no upper limit to the number of variables that can be displayed on each screen (page), only limited by screen size and refresh performance. The maximum page size is 32 lines (text lines), which means that a considerable number of data fields can be arranged in one screen. Variable types support common industrial formats such as bit, byte, word, doubleword, floating-point number, and BCD code. When designing complex recipe input screens or parameter lists, the capacity of 32 rows can even exceed the single page display capability of some 10 inch color HMIs.

4.3 Macro Editor

The macro engine built into BKDR-16 allows users to execute script logic in events such as button presses, screen opens, and timer overflows. The macro instruction set includes mathematical operations, comparisons, jumps, serial port sending, bit operations, etc. A typical application scenario: Without the involvement of a PLC, directly calculate the difference between two data registers within the HMI and determine if it exceeds the limit, then control a function key LED to flash and alert the operator. This edge computing capability greatly reduces the logic burden of small PLCs.

4.4 Historical Events and Formulas

The historical event list can record 256 events with timestamps, which are sourced from the hardware clock/calendar. This RTC uses an independent backup battery (usually CR2032) that can continue to run for at least one year after the main power supply is disconnected. For GMP or ISO traceability systems that require traceability of operation records (such as who modified the set temperature at what point), this function is indispensable.

The recipe function provides 16KB of non-volatile storage space, which can be divided into multiple independent recipe tables. Each recipe table can store a set of process parameters, such as pressure, speed, and temperature range of the injection molding machine. The operator selects the recipe number through the keyboard, downloads it to the PLC with one click, or uploads and saves the current PLC value as a new recipe. 16KB may not seem large, but it is enough to accommodate hundreds of floating-point numbers or thousands of integer parameters.

4.5 Security and Peripherals

The password protection function supports multi-level permissions at the operator level, engineer level, and administrator level, with different screens and operable function keys visible at different levels. In addition, BKDR-16 also retains a standard parallel or serial printer interface that can hard copy alarms, events, and current images to compatible industrial printers - which remains a compliance requirement in the chemical and pharmaceutical industries that require paper record archiving.

Typical Engineering Application Scenarios

Scenario 1: Monitoring and renovation of old air compressor units

A certain factory has three Ingersoll Rand air compressors produced in the 1990s, each with only a simple indicator panel, no communication interface, only dry contact signals (operation, fault, temperature switch) and 4-20mA analog signals (exhaust pressure, oil temperature). Engineers use BKDR-16 as the central operating station: analog signals are connected to PLCs (such as Siemens S7-1200 or domestic compatible modules), and dry contact signals are directly isolated by optocouplers and connected to the digital input expansion of BKDR-16 (through external I/O modules via communication ports). Use a macro editor to convert pressure and temperature into actual engineering values, and draw trend curves on a 320 × 240 screen. The operator can achieve start stop and parameter switching of three units through 14 function keys, without the need to learn complex touch screen menus.

Scenario 2: Operating terminal outside the explosion-proof area

In the petrochemical plant area, operators must remotely monitor the temperature of the reactor and the status of the agitator in a safe area. Due to the presence of flammable gases on site, conventional touch screens cannot be used (capacitive screens cannot be operated with gloves, and explosion-proof touch screens are expensive). BKDR-16 is equipped with an explosion-proof installation box, and all operations are completed through physical buttons. The monochrome LCD is still clear and readable under strong outdoor light. The UniNET client function of the device simultaneously reads two different PLC systems (one responsible for the reactor and the other for the tank area), and displays key data on the same page, avoiding operators from running back and forth between two computers.

6、 Common troubleshooting and on-site maintenance guide

Based on years of on-site maintenance experience and the hardware characteristics of BKDR-16, the following are the six most common types of fault phenomena, cause analysis, and handling steps. Be sure to disconnect the 24V power supply before performing any maintenance operations.

Fault 1: The screen has no display, but the power indicator light is on

Possible reasons:

LCD contrast potentiometer drifts or is mistakenly set to the lowest.

Backlight inverter damaged (monochrome LCD usually has CCFL backlight).

The wiring between the motherboard and LCD is loose or oxidized.

Troubleshooting steps:

Press the preset "contrast+" function key on the keyboard (usually configured on a certain function key) or enter the system menu to adjust the contrast.

Observe whether there is a faint halo at the edge of the screen in a dark environment. If not, it indicates a backlight malfunction.

Disassemble and inspect the cable plug, clean the gold finger with an eraser, and re insert it tightly.

Fault 2: Communication with PLC is intermittent or completely disconnected

Possible reasons:

The communication parameters (baud rate, data bits, checksum) do not match.

The RS-485 bus is not connected to a terminal resistor or the A/B lines are reversed.

Using the wrong physical interface (e.g. selecting RS-232 mode but actually wiring RS-485).

For the 20 mA current loop mode: the loop power supply is missing or the current loop polarity is reversed.

Troubleshooting steps:

Use a serial port monitoring tool (such as a PC with a serial port debugging assistant) to intercept the message sent by BKDR-16 and confirm if there is any data output.

Connect BKDR-16 and PLC separately point-to-point (excluding bus interference), gradually increasing the number of nodes.

Check if the mode switch on the back of the device matches the settings in the configuration software.

For the current loop, use a multimeter to measure the loop current (which should normally vary dynamically between 0-20mA or 4-20mA).

Fault 3: Some keys on the keyboard do not respond or all keys fail

Possible reasons:

The keyboard membrane or conductive rubber is aging (the lifespan of physical keys is usually 1 million times).

The keyboard matrix cable is broken or the plug is detached.

The system has entered a password lock screen state.

Troubleshooting steps:

Restart the HMI, continuously press any key during the self check process, observe if there is a buzzer sound, and determine if the hardware recognizes it.

Enter the system information page (usually by holding down a specific function key when powered on) and test the key matrix.

If a hardware malfunction is confirmed, the same model of keyboard conductive adhesive or the entire keyboard board can be replaced (the keyboard module of BKDR-16 can be separated and replaced).

Fault 4: The program cannot be downloaded or uploaded

Possible reasons:

PC serial port or USB-RS232 conversion cable is not compatible (some inexpensive conversion cables cannot stably support hardware flow control).

HMI program memory is full or Flash is damaged.

The download protocol selection is incorrect (BKDR-16 requires the use of UniOP specific download protocol, not Modbus).

Troubleshooting steps:

Use a genuine RS-232 port (desktop native serial port) or high-quality converter (such as FTDI chip solution).

Attempt to erase the entire user memory and download again (note to backup recipe data).

Remove the memory expansion board and only use the onboard 512KB for testing to rule out poor contact of the expansion card.

Fault 5: Reset clock/calendar to year 2000 after each power outage

Possible reasons:

The backup battery is depleted. BKDR-16 uses replaceable CR2032 lithium batteries with a lifespan of approximately 3-5 years.

Repair steps:

Disconnect the 24V power supply, open the back cover, and find the battery holder (usually located in the upper right corner of the PCB).

Replace the battery with a new one (pay attention to the positive and negative poles).

After powering on again, enter the system settings menu to manually calibrate the time.

If it still cannot be saved after replacement, check the battery socket solder joints or whether there is a short circuit.

Fault 6: Printing output garbled or printer unresponsive

Possible reasons:

The baud rate and data format of the printer and HMI do not match.

The correct printer model (such as ESC/POS, EPSON standard) has not been selected.

Print buffer overflow.

Troubleshooting steps:

Connect the printer to the PC serial port and use a serial port tool to send a simple ASCII string (such as "Hello") to verify if the printer is functioning properly.

Reduce the printing baud rate in the engineering settings of BKDR-16 (such as 9600 instead of 19200).

Reduce the amount of data for a single print (for example, changing from printing 10 alarms at once to pagination printing).

Replacement and upgrade path

Due to the discontinuation of BKDR-16, engineers need to consider replacement solutions when irreparable hardware failures occur in the device, such as motherboard burnout, LCD fragmentation, and lack of spare parts. Here are three mainstream paths:

Path 1: Replacement of successor models in the same series

UniOP subsequently launched the eTOP series (such as eTOP 507), upgrading the screen to a 5.7-inch color TFT, but still retaining physical function key options, and the communication port is compatible with the RS-232/485 configuration of BKDR-16. When replacing, simply update the original project files to the target model through UniOP Designer and recompile them, with almost no need to modify the connecting cables.

Path 2: Cross brand replacement with domestically produced HMI with physical buttons

Currently, multiple domestic brands (such as BuKe, WeiKong, and XinJie) offer HMI models with 5.6-inch or 7-inch, 12-16 physical buttons at a low price. Attention should be paid when replacing:

Confirm whether the number of keys meets the original function key mapping;

Check if it supports 20 mA current loop communication (most domestic HMIs do not support it, in which case an external current loop to RS-232 active converter is required);

Rewrite all screens and alarm logic, which requires a significant amount of work.

Path 3: Transform into an industrial computer+configuration software

If BKDR-16 in the original system is responsible for a large amount of macro computing and UniNET server functions, it can be considered to replace it with a fanless industrial computer running SCADA software (such as KingView, InTouch), and switch physical keys to USB industrial keyboard mapping. This method has a high cost, but greatly improves scalability and computing power, making it suitable for situations where data analysis capabilities need to be added in the future.

Regardless of which path is chosen, it is recommended to export all recipe data and historical event lists through its printer port before retiring BKDR-16 as a benchmark for the new system setup.