Unitech MS852B troubleshooting guide: errors, faults and fixes

Short answer: According to the Unitech light table, red flashing every 2 seconds indicates a battery below 10%, and fast flashing a battery below 5% (the other lights are then disabled). Recharge the scanner. Red alternating every second for 5 seconds indicates a system warning or error.

Likely cause

§ 1.7 of the MS852B manual (LED / Beeper Indicator) describes these three states of the red light, on the outer ring for low battery. For the system warning, the light alternates for 5 seconds or until the trigger is pressed; the manual does not detail the errors concerned.

Caution: Use only genuine Unitech batteries: replacing the battery with an incorrect type presents a risk of explosion. Only charge the battery between 0 °C and 40 °C, never below 0 °C.

What to do

1. Flashing every 2 seconds or fast flashing: place the scanner on its base or connect it to a PC with the supplied USB-C cable (see the entry on charging).
2. Red alternating for 5 seconds: press the trigger to stop the signal. The manual does not specify which errors trigger it.
3. The warning signal can be given by the beeper (default), the vibration motor, both, or neither: “System Warning/Error Indicator” setting in the manual.

Sources: 1.7 LED / Beeper Indicator (opens in a new window) – MS852B User Manual V1.7 · 2.13 System Warning/Error Indicator (opens in a new window) – MS852B User Manual V1.7 · 1.7 LED / Beeper Indicator (opens in a new window) – MS852B Plus User's Manual V1.7 (official documentation).

Short answer: When not charging, a solid green light means, according to Unitech, that the scanner is paired but disconnected from the host. On the base, solid green indicates that the host is connected but the paired scanner is disconnected. Bring the scanner closer to its base and check that it is switched on: the link is restored when both lights change to solid blue.

Likely cause

§ 1.7 of the MS852B manual distinguishes solid green (paired, disconnected), green alternating every second (system busy, scanning or sending disabled) and, on the new MS852B placed on charge, the solid green of charging complete.

What to do

1. If the scanner is charging, solid green indicates a full battery (new MS852B): this is not a fault.
2. Otherwise, check that the scanner is switched on (press the trigger for 2 seconds, long beep).
3. Bring it closer to the base: the stated range is 100 m in open space.
4. Wait for the scanner and base lights to change to solid blue (connected and ready).
5. Green alternating every second: the system is busy and scanning or sending is disabled; wait for the operation to finish.
6. If the link does not return, pair again (see pairing the scanner and its base).

Sources: 1.7 LED / Beeper Indicator (opens in a new window) – MS852B User Manual V1.7 · 1.3 Specifications (opens in a new window) – MS852B User Manual V1.7 · 1.7 LED / Beeper Indicator (opens in a new window) – MS852B Plus User's Manual V1.7 (official documentation).

Short answer: According to Unitech, blue alternating every second indicates pairing mode; fast blue flashing indicates that the scanner is connected but the signal is too weak. In the second case, bring it closer to its base or the host.

Likely cause

The light table (§ 1.7) describes these two states for the scanner; the base also shows alternating blue in pairing mode.

What to do

1. Blue alternating every second: the scanner is waiting for pairing. Place it on its base (automatic pairing) or complete the Bluetooth pairing with the host.
2. Fast blue flashing: bring the scanner closer to the base or the host.
3. Pairing complete: the scanner and the base show solid blue.
4. In BLE, setting “RF signal checking” to the high level (Higher Level) makes the link more reliable but reduces the range; the normal level is the default setting.

Sources: 1.7 LED / Beeper Indicator (opens in a new window) · 2.6 Bluetooth (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: The number of beeps at power-on indicates the operating mode: 1 beep for Auto, 2 beeps for Wedge, 3 beeps for Batch. Three beeps therefore mean that the scanner is in Batch mode: scans are stored in a batch file, which is sent with the “Send Batch” barcode.

Likely cause

The beep table (§ 1.7) associates the number of beeps with the mode selected in “Operation Mode” (§ 2.2).

What to do

1. Count the beeps at power-on: 1 (Auto), 2 (Wedge) or 3 (Batch).
2. To send the stored scans, scan the “Send Batch” barcode (§ 2.4, Data & Memory).
3. To return to immediate transmission, scan the barcode for the mode you want in the “Operation Mode” section of the manual.
4. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: 1.7 LED / Beeper Indicator (opens in a new window) · 2.2 Operation Mode; 2.4 Data & Memory (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: This is the automatic shutdown alarm: the scanner emits three short beeps 15 seconds before switching off after a period of inactivity. The default delay is 15 minutes; it can be set from 5 minutes to 6 hours, or disabled.

Likely cause

§ 2.8 (Auto Power Off After Idle) and the beep table (§ 1.7) describe the automatic shutdown and its alarm.

What to do

1. Press the trigger for 2 seconds to switch the scanner back on (long beep).
2. To change the delay, scan the barcode you want in the “Auto Power Off After Idle” section: 5 or 30 minutes, 1, 2, 4 or 6 hours, or Disable.
3. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: 1.7 LED / Beeper Indicator (opens in a new window) – MS852B User Manual V1.7 · 2.8 Auto Power Off After Idle (opens in a new window) – MS852B User Manual V1.7 · Auto power off (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 (official documentation).

Short answer: Check two settings: the beeper may be set to Mute or Disable, and the good read indication to the vibration motor or None. Restore the volume in “Beeper Control” (Medium by default) and the “Good Read Indicator” to Beeper.

Likely cause

The manual offers five beeper levels (Disable, Low, Medium by default, High, Mute) and four good read indicators (None, Beeper by default, Vibrator, Beeper & Vibrator).

What to do

1. Scan the level you want in the “Beeper Control” section (§ 2.9): Low, Medium or High.
2. In “Good Read Indicator” (§ 2.10), choose Beeper or Beeper & Vibrator.
3. The vibration motor is enabled by default (§ 2.17, Vibrator Control).
4. A good read is also indicated by a green flash of the light.
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Source: 2.9 Beeper Control; 2.10 Good Read Indicator; 2.17 Vibrator Control (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Check that the symbology is enabled: according to the MS852B manual, Code 11, Interleaved 2 of 5 and Discrete 2 of 5 are disabled by default. Once enabled, the 2 of 5 codes only accept one length by default (14 characters for ITF, 12 for D 2 of 5). Keep the trigger pressed during scanning: this is the default mode.

Likely cause

Chapter 3 (Symbology) of the manual gives the default values: Code 128, GS1-128, ISBT 128, Code 39, Code 93 and Codabar are enabled; Code 11, Interleaved 2 of 5, Discrete 2 of 5 and Trioptic Code 39 are disabled, as is Code 39 Full ASCII conversion. The default scan mode (Trigger, Level) decodes as long as the trigger is pressed, until decoding or release.

Caution: Do not disable Code 128: the manual warns that the programming barcodes might then no longer be recognised. The scanner contains a visible laser diode; Unitech warns that controls or settings other than those in the manual may result in exposure to hazardous laser radiation and that optical instruments (binoculars, magnifying glasses) increase the risk to the eyes.

What to do

1. Test on a Code 128 or Code 39 barcode, which are enabled by default: a green flash and a beep confirm the scan.
2. For an ITF (Interleaved 2 of 5), Code 11 or Discrete 2 of 5 barcode, scan the symbology's enable barcode in chapter 3 of the manual.
3. If the enabled barcode is still not read, set its length: “Length Within Range” or “Any Length” instead of the default single length. Unitech nevertheless recommends specific lengths, as a partial read may return less data than the barcode contains.
4. Code 39 containing extended characters: enable “Code 39 Full ASCII”; the manual then advises the “Length Within Range” or “Any Length” lengths.
5. Keep the trigger pressed: the decode session lasts 3 seconds by default (adjustable from 0.5 to 3 seconds in “Decode Session Timeout”).
6. To return to a known configuration, see resetting.
7. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: 3.1 UPC/EAN/JAN (Code 128); 3.2 Code 39; 3.3 Code 93; 3.4 Code 11; 3.5 Interleaved 2 of 5; 3.6 Discrete 2 of 5; 3.7 Codabar (opens in a new window) · 2.26 Scan Mode; 2.30 Decode Session Timeout; Laser Information (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Enable automatic presentation mode (Auto Presentation Mode, disabled by default): the scanner then reads on its own when placed on its base, and returns to trigger mode when removed. Off the base, the “Presentation (Blink)” scan mode starts scanning as soon as a barcode enters the field of view.

Likely cause

§ 1.9 describes automatic presentation mode on the base; § 2.26 (Scan Mode) offers four modes: Trigger (Level) by default, Presentation (Blink), Auto Aim and Auto Aim with Illumination.

What to do

1. For automatic scanning on the base, scan the “Enable” barcode in the “Auto Presentation Mode” section.
2. Place the scanner on its base: the green light flashes every 2 seconds. When removed, it returns to trigger scanning.
3. Alternatively: in “Scan Mode”, choose Presentation (Blink); the illumination switches off after a period of inactivity until movement is detected.
4. In low light, “Low Light Scene Detection” (presentation mode) can keep the aimer on (Aiming Pattern Assist) or a dimmed illumination (Dim Illumination Assist).
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: 1.9 Auto Presentation Mode; 2.26 Scan Mode; 2.37 Low Light Scene Detection (opens in a new window) – MS852B User Manual V1.7 · Scan modes (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 (official documentation).

Short answer: In keyboard emulation (HID), the keyboard language is set to US English by default. Scan the “French” barcode in the “HID Keyboard Language” section to match a French host computer; Belgian and Swiss keyboards also have their own barcode.

Likely cause

§ 2.21 of the manual (HID Keyboard Language) lists the available languages: US English (default), UK English, German, Japanese, Danish, Spanish, Swiss, Swedish, French, ALT Mode, Belgian, Norwegian and Italian.

What to do

1. Scan the “French” barcode in the “HID Keyboard Language” section (or Belgian, Swiss depending on the host computer's keyboard).
2. Test in a text editor.
3. If letter case is a problem, “HID Keyboard Case” offers To Upper, To Lower or Auto Trace (default).
4. The manual also offers an inter-character delay (“HID Keyboard Character Delay”: 1 ms by default, then 5, 10, 20, 50 or 100 ms).
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

The manual does not mention AZERTY by name: the “French” option corresponds to the French keyboard layout.

Sources: 2.19 HID Keyboard Character Delay; 2.20 HID Keyboard Case; 2.21 HID Keyboard Language (opens in a new window) – MS852B User Manual V1.7 · 2.20 HID Keyboard Language (opens in a new window) – MS852B Plus User's Manual V1.7 (official documentation).

Short answer: The terminator added after each barcode is set in “Data Terminator”: CR (default), CRLF, LF, None/Null or TAB. For a custom prefix or suffix, use the “Prefix/Suffix Values” section.

Likely cause

§ 2.7 (Data Terminator) sets the end character; § 2.34 (Prefix/Suffix Values) allows you to add a prefix or suffix, coded on four digits, the default value being the Enter key (CR LF, code 7013).

What to do

1. To change the line ending, scan the barcode you want in “Data Terminator”: CR, CRLF, LF, None/Null or TAB.
2. For a prefix or suffix: first set “Scan Data Transmission Format” (Data As Is by default) to a format that includes the prefix or suffix.
3. Then scan the “Prefix” or “Suffix” barcode, followed by the four numeric barcodes for the value, taken from appendix B (Numeric Barcodes).
4. The manual advises against using ADF rules at the same time as this setting.
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: 2.7 Data Terminator; 2.34 Prefix/Suffix Values; 2.35 Scan Data Transmission Format (opens in a new window) – MS852B User Manual V1.7 · HID keyboard settings (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 (official documentation).

Short answer: First check the lights: the scanner and the base must be solid blue. A base showing solid red is powered but cannot see the host: check the cable and the interface selector (USB HID on the left by default). If the scanner emits 3 beeps at power-on, it is in Batch mode and stores the scans.

Likely cause

The manual distinguishes the good read beep when Bluetooth is connected (medium beep) from the one emitted when it is disconnected (short medium-high beep). The base light table shows solid red (powered, host not connected), solid green (host connected, scanner disconnected) and solid blue (ready).

What to do

1. Base solid red: check the interface cable between the base and the PC, and the position of the interface selector (USB or RS-232).
2. Base solid green: the scanner is paired but disconnected; bring it closer and see the entry on the solid green light.
3. Short, higher-pitched scan beep: the scanner is not connected via Bluetooth at the time of scanning.
4. Three beeps at power-on: Batch mode, the scans are stored (see the entry on the three beeps).
5. With RS-232, check the port parameters (see the RS-232 entry).

Sources: 1.7 LED / Beeper Indicator (opens in a new window) · 1.4 Getting Started; 1.8 Firmware Update Procedure (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Scan “Send Batch” to send the scans stored in Batch mode. To clear the memory, scan “Enter Batch File” then “Erase” (or “Enter Auto Buffer Erase” then “Erase” for the Auto mode buffer).

Likely cause

§ 2.4 (Data & Memory) groups together sending and erasing data; § 2.22 states that, by default, the buffer is not kept at power-off (Don't Save).

What to do

1. Sending the batch: scan “Send Batch”.
2. Erasing the batch: scan “Enter Batch File”, then “Erase”.
3. Erasing the Auto buffer: scan “Enter Auto Buffer Erase”, then “Erase”.
4. To delete only the last scan: “Erase Last Data Entry”; to see the free space: “Free Buffer / Drive Space”.
5. To keep the buffer at power-off, choose “Save” in “Save Buffer When Power Off”.
6. “End of Batch Sending Message” option: at the end of sending, the scanner adds a line with the number of entries and a checksum.
7. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Source: 2.4 Data & Memory; 2.22 Save Buffer When Power Off; 2.24 End of Batch Sending Message (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Set the base's interface selector to USB or RS-232 and connect it to the PC. Switch the scanner on (trigger for 2 seconds), then place it on the base: pairing starts on its own and finishes when both lights are solid blue.

Likely cause

§ 1.4 (Getting Started) of the MS852B manual and the quick start guide describe automatic pairing on the base (Enable Cradle Auto Pair, default setting).

What to do

1. Choose the interface with the base's selector: USB HID on the left (default setting) or RS-232.
2. Connect the base to the PC with the interface cable (the RS-232 cable is used with a mains adapter).
3. Switch the scanner on: press the trigger for 2 seconds, long beep.
4. Place it on the base: Bluetooth pairing starts automatically.
5. Pairing is complete when the scanner and the base show solid blue; the Bluetooth connection is indicated by a low-medium-high beep sequence.
6. If automatic pairing does not start, check that “Disable Cradle Auto Pair” has not been scanned (§ 2.6).

Sources: 1.4 Getting Started; 2.6 Bluetooth (opens in a new window) – MS852B User Manual V1.7 · Pairing with the cradle (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 · 1.7 LED / Beeper Indicator (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: According to the Unitech FAQ, hold the trigger for more than 10 seconds: the scanner deletes its last pairing. On the base side, pressing the button for 2 seconds unpairs it from the scanner.

Likely cause

The MS852B FAQ (and the MS852B Plus FAQ) gives the trigger method; § 1.4 of the manual describes the functions of the base button.

Caution: Pressing the base button for 5 seconds resets it to its default settings: release it at 2 seconds for a simple unpairing.

What to do

1. Scanner: hold the trigger for more than 10 seconds.
2. Base: hold its button for 2 seconds.
3. Another method: the “BT/BLE Un-Pair / Pair” barcode in the Bluetooth section of the manual.
4. Then pair again (see pairing the scanner and its base).
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: Accessory – How do I remove pairing? (opens in a new window) – MS852B FAQ (Unitech) · Accessory – How do I remove pairing? (opens in a new window) – MS852B Plus FAQ (Unitech) · 1.4 Getting Started (Cradle button) (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Without the base, the scanner connects directly to the host over Bluetooth, as a keyboard (BT Keyboard or BLE Keyboard) or as a serial port (BT SPP). To change type, first remove the pairing, scan the new type, then reconnect over Bluetooth.

Likely cause

§ 2.1 (Scanner Type) specifies that these settings only apply in mode without base. The scanner is dual-mode: Bluetooth LE 4.2 and Bluetooth 2.1+EDR class 1, HID and SPP profiles.

What to do

1. Remove the current pairing (see removing the pairing).
2. Scan the connection type you want: BT Keyboard, BLE Keyboard or BT SPP.
3. Start Bluetooth pairing from the host.
4. In SPP, automatic reconnection (Auto Connection) is enabled by default.
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

The Unitech manual does not detail the pairing steps on the computer or phone side.

Sources: 2.1 Scanner Type; 2.2 Operation Mode; 2.5 BT SPP Setting; 1.3 Specifications (opens in a new window) – MS852B User Manual V1.7 · Connecting to a host (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 (official documentation).

Short answer: Fast blue flashing indicates a signal that is too weak; solid green, a scanner that is paired but disconnected. Move closer to the base: the stated range is 100 m in open space. A short press on the base button lets you locate the paired scanner.

Likely cause

The light table (§ 1.7) and the specifications (§ 1.3) in the MS852B manual. In BLE, the “Higher Level” setting of the radio signal check makes the link more reliable but shortens the range.

What to do

1. Bring the scanner closer to the base, avoiding obstacles.
2. Check the scan beep: a short, higher-pitched beep indicates a scan made while Bluetooth is disconnected.
3. To locate a misplaced scanner, briefly press the button on the base.
4. In BLE, if the link is unstable, try “Higher Level” in “RF signal checking” (reduced range); “Normal Level” is the default setting.
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Sources: 1.7 LED / Beeper Indicator (opens in a new window) · 1.3 Specifications; 1.4 Getting Started; 2.6 Bluetooth (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Set the base's interface selector to RS-232, use the RS-232 cable with its mains adapter, and set the host port to match the scanner: by default 9600 baud, 8 data bits, no parity, 1 stop bit, no flow control.

Likely cause

§ 2.38 (RS232 Setting) of the manual lists the serial parameters and their default values.

What to do

1. Set the base's interface selector to the RS-232 position and connect the base to the serial port with the RS-232 cable and the mains adapter.
2. Set the host port: 9600 baud (19200 to 230400 possible), parity None (Odd, Even), 1 stop bit (or 2), 8 data bits (or 7).
3. Hardware flow control: None by default (Standard RTS/CTS and options 1 to 3 possible). Software: None by default (ACK/NAK, ENQ, ACK/NAK with ENQ, XON/XOFF).
4. If you change a parameter on the scanner, scan the corresponding barcode in the RS232 Setting section and apply the same value on the host.
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

Source: 2.38 RS232 Setting; 1.4 Getting Started (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: Charge the scanner on its base or with the supplied USB-C cable connected to a PC, between 0 °C and 40 °C. The light is solid red while charging. When charging is complete, it changes to solid green on the new MS852B and goes off on the original version.

Likely cause

§ 1.5 states a full charge in about 5 hours (less than 6.5 hours according to the specifications) and asks you to use only the supplied USB-C cable. The battery notice prohibits charging below 0 °C.

Caution: Unitech asks you to use only the supplied adapter or an adapter with the same specification, not to use it outdoors or expose it to water or humidity, and to unplug it when the battery is full.

What to do

1. Charge the battery before first use.
2. Place the scanner on its powered base, or connect it to a PC with the supplied USB-C cable.
3. Solid red light: charging in progress. Allow about 5 hours for a full charge.
4. Charging complete: solid green (new MS852B) or light off (original MS852B).
5. Only charge between 0 °C and 40 °C; do not charge a battery that heats up after a long period of inactivity.
6. In a vehicle, the Unitech FAQ states that a USB-C cigarette lighter adapter is suitable, as the scanner charges through a standard USB-C connector.

For choosing the USB cable, the Unitech FAQ refers to the list of MS84X and MS85X USB cables.

Sources: 1.5 Battery Charging; 1.7 LED / Beeper Indicator; Battery Notice; Adapter Notice (opens in a new window) – MS852B User Manual V1.7 · Charging (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 · Accessory – USB cable; car adapter (opens in a new window) – MS852B FAQ (Unitech) (official documentation).

Short answer: Unitech advises replacing the battery about once a year or after 500 charge cycles, and as soon as its performance drops by more than 20%. A battery that swells or changes shape must no longer be used. The MS852B battery (2850 mAh) is replaceable.

Likely cause

The battery notice in the MS852B manual sets these criteria; the specifications state a replaceable 2850 mAh battery and 20 hours of battery life.

Caution: Use only genuine Unitech batteries: replacing the battery with an incorrect type presents a risk of explosion. Only charge the battery between 0 °C and 40 °C, never below 0 °C.

What to do

1. Compare the current battery life with that of a new battery: beyond a 20% loss, replace it.
2. Also replace it after about a year or 500 cycles.
3. Use only a genuine Unitech battery: damage caused by a third-party battery is not covered by the warranty.
4. For prolonged storage, keep the battery at about 40% charge, in a cool place (from -20 °C to 60 °C, ideally at room temperature), and avoid discharging it completely.

When to call a technician: the battery has swollen or changed shape: Unitech asks you to stop using it and to dispose of it in accordance with the applicable rules.

The replacement procedure in § 1.6 is illustrated in the manual; these illustrations were not consulted for this guide.

Source: Battery Notice; 1.3 Specifications; 1.6 How to Replace Battery (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: To switch it on, hold the trigger for 2 seconds until the long beep. To switch it off, hold it for about 7 seconds until the short beep. If nothing happens, recharge the battery.

Likely cause

§ 1.4 of the MS852B manual and the quick start guide describe switching on and off with the trigger.

Caution: Do not hold the trigger for more than 10 seconds: according to the Unitech FAQ, the scanner then deletes its last pairing.

What to do

1. Power-on: press the trigger for 2 seconds, long beep.
2. Power-off: press for about 7 seconds, short beep.
3. No response: place the scanner on its base or connect the USB-C cable (see the entry on charging).
4. The scanner also switches off on its own after 15 minutes of inactivity by default (see automatic shutdown).

Sources: 1.4 Getting Started (opens in a new window) – MS852B User Manual V1.7 · Power on/off (opens in a new window) – MS852B Bluetooth 2D Barcode Scanner Quick Start Guide V1.0 · Accessory – How do I remove pairing? (opens in a new window) – MS852B FAQ (Unitech) (official documentation).

Short answer: Scan the “Factory Default” barcode in the “System Reset & Info” section of the manual: it restores the factory settings and erases the Bluetooth pairing information. To keep the pairing, scan “Reset Setting” instead. The base is reset by pressing its button for 5 seconds.

Likely cause

§ 2.3 (System Reset & Info) of the MS852B manual and the MS852B Plus manual distinguishes the two barcodes; § 1.4 describes the base button.

What to do

1. Open the Unitech user manual at the “System Reset & Info” section (chapter 2).
2. Scan “Factory Default” to restore everything, pairing included, or “Reset Setting” to restore the settings while keeping the Bluetooth pairing key.
3. To reset the base, hold its button for 5 seconds.
4. Then pair again if necessary (see pairing the scanner and its base), and redo your settings (keyboard language, terminator).
5. The programming barcodes are in the Unitech user manual: they are not reproduced here.

The quick start guide presents these barcodes with slightly different labels; we follow the V1.7 user manual.

Sources: 2.3 System Reset & Info; 1.4 Getting Started (Cradle button) (opens in a new window) – MS852B User Manual V1.7 · 2.3 System Reset & Info (opens in a new window) – MS852B Plus User's Manual V1.7 (official documentation).

Short answer: On the MS852B product page, Unitech offers the Scanner Configuration Manager, a Windows application that synchronises, modifies, sends and retrieves the scanner's settings. The page also offers the Easy Setting Codes Generator and, for the MS852B Plus, an Android ScannerSDK.

Likely cause

The Unitech MS852B and MS852B Plus product pages list these tools in their downloads, alongside the manual and the programming barcodes.

What to do

1. Download the Scanner Configuration Manager from the Unitech product page for the model (MS852B or MS852B Plus).
2. Use it on a Windows PC to read, modify and then send back the configuration.
3. For a one-off setting, scan the programming barcodes in the user manual.
4. To find out the scanner's version and information, scan “Send Info” (System Reset & Info section): the scanner sends its information to the host.

The documentation consulted does not describe how these tools work in detail.

Sources: MS852B Bluetooth 2D Imager Scanner │ Unitech (opens in a new window) – Unitech MS852B product page · MS852B Plus High Performance Bluetooth 2D Imager Scanner │ Unitech (opens in a new window) – Unitech MS852B Plus product page · 2.3 System Reset & Info; 1.8 Firmware Update Procedure (opens in a new window) – MS852B User Manual V1.7 (official documentation).

Short answer: The update is done through the base connected via USB serial and the Tera Term software (Y-modem protocol). Unitech recommends Tera Term V4.72 if another version fails. Unpair the scanner from the base before updating it.

Likely cause

§ 1.8 (Firmware Update Procedure) describes updating the base and then the scanner; the white light indicates update mode. The MS852B FAQ specifies that some versions of Tera Term do not complete the update successfully.

Caution: Pressing the base button for 5 seconds also resets it to its default settings: pair again and redo your settings if necessary.

What to do

1. Base: set the interface selector to USB serial (the side opposite the RJ45 port), hold the base button while connecting the USB cable to the PC: the white light flashes.
2. In Tera Term, choose the COM port, then Transfer > Y-modem > Send and the firmware file. The blue light flashes when the update has succeeded.
3. Scanner: unpair it from the base. With the base in USB serial mode and connected to the PC, wait for the flashing blue light and select the COM port in Tera Term.
4. Do not switch the scanner on and do not place it on the base. Press the PC's space bar, then the trigger: a beep and the flashing white light indicate bootloader mode.
5. Send the file with Transfer > Y-modem > Send. The update has succeeded when you hear a beep followed by the white light going off.
6. Check the scanner's version by scanning “Send Info”. For the base, the manual says to set the interface to USB HID, open a text editor and hold the button until “factory default” appears.

Sources: 1.8 Firmware Update Procedure (opens in a new window) – MS852B User Manual V1.7 · Utility – Tera Term version (opens in a new window) – MS852B FAQ (Unitech) · 1.7 LED / Beeper Indicator (opens in a new window) – MS852B User Manual V1.7 (official documentation).