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  5. Select Series | 48mm x 48mm  L91

Select Series | 48mm x 48mm

L91
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Safety Limit Controller

• Universal input: TC, RTD, mV, V, mA
• Latching relay for safety interlock
• Dual display for PV and setpoints
• RS-485 & retransmission support
• USB config via programming port

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Features

  • 1/16 DIN compact panel mounting
  • 4-digit LED display with status icons
  • Output indicators (OP1, OP2), °C/°F display
  • Scroll / Up / Down / Reset key interface
  • Manual reset and remote reset support
  • Lockout function for secure operation
  • Alarm annunciator and event input available
  • Output 2 supports alarm, RS-485, power, retransmit
  • Sampling rate: 5 times per second
  • 18-bit A/D resolution for high precision

  • PV shift and digital filtering function
  • Optional DC power supply for sensors
  • Firmware upgrade via programming port
  • CE, UL61010, and EN61326 certified
  • Modbus RTU protocol support via RS-485

L91 Limit Controller
Compact Safety for Temperature Protection  

Designed for industrial over-temperature monitoring and alarm safety  

The L91 from BrainChild is a microprocessor-based limit controller engineered for precise over-temperature protection in industrial systems. With universal input compatibility (TC, RTD, voltage, current), latching relay output, and dual display interface, the L91 ensures fast and reliable safety responses. Its output flexibility includes relay, SSR, or TRIAC, while Output 2 supports expansion to alarms, Modbus communication, or analog retransmission. Users can configure the controller via front keys, RS-485, or the USB programming port using BC-SET Pro software. Certified for CE, UL, and EN standards, L91 is ideal for oven safety, thermal processing, plastic molding, or automation panels that require compact, accurate, and durable temperature control devices.  

Real-Time Display with Function Keys

Monitor PV, outputs, alarms, and status at once  

The L91 panel adopts a compact yet efficient layout, featuring a high-visibility 4-digit red LED display to present real-time process values (PV). Clear status indicators such as OP1 and OP2 provide immediate visual feedback for output activation, while °F and °C symbols indicate selected temperature units. Additional labels like "PV", "SP1", "SP2", "MAN", and "AT" are embedded to support operator recognition across operating or tuning states. The four-key interface includes Scroll, Up, Down, and Reset (R) buttons, allowing users to navigate menus, adjust parameters, and reset alarms efficiently. The Reset key also supports unlock/confirm actions via long press. The panel further includes a LOCK status LED, which secures access against unauthorized configuration changes. This user interface simplifies configuration and enhances operational safety in field deployment, OEM integration, or panel system control.  

Universal Input Compatibility for Accurate Monitoring

Supports TC, RTD, Voltage, Current, and mV Signals

The L91 is equipped with a high-precision 18-bit A/D converter and supports a wide variety of input signals including thermocouples (J, K, T, E, B, R, S, N, L), RTDs (PT100 DIN and JIS), low voltage (mV), standard voltage (0–1V, 0–10V), and current (0–20mA). With a sampling rate of 5 times per second (200ms), it ensures rapid response and stable measurement. Adjustable parameters include decimal point location, PV offset, and display resolution. Additional protections such as sensor break detection and programmable digital filtering enhance system reliability and measurement stability.

Dual Channel Outputs for Limit, Alarm, and Sign  

Relay, SSR, TRIAC Outputs + Optional RS-485 or

The L91 provides two output channels—Output 1 is dedicated for primary limit control using relay (2A/240VAC), SSR drive (5V/30mA or 14V/40mA), or TRIAC (1A continuous, 20A surge). Output 2 is configurable for alarm output, RS-485/RS-232 communication, retransmission (4–20mA, 0–10V, etc.), event input, or DC power supply (5V, 12V, 20V). High/low limit control, alarm modes (normal, latching), and programmable logic enable the L91 to adapt to diverse process safety and automation scenarios .

Offline Programming via Dedicated Cable

Clone settings, update firmware, calibrate via PC  

The L91 features a built-in programming port designed specifically for efficient offline setup, system calibration, and maintenance operations. By using the official CC91-2 communication cable in conjunction with BrainChild’s configuration software, users can conveniently connect the device to a PC to replicate settings across multiple units, perform firmware upgrades, and carry out factory calibrations. This direct-access interface is especially beneficial in OEM, system integrator, or production line environments where uniformity and rapid deployment are essential. Unlike conventional USB ports, the programming port utilizes a proprietary connection to ensure stable, interference-free communication and avoid accidental field changes. Moreover, it operates independently of baud rate, address, or stop bit settings, allowing for plug-and-play-like functionality during initial installation phases.  

BC-SET Pro Configuration Software

Easy parameter setup and firmware upgrade for Core Series controllers

BC-SET Pro is the official configuration software for BrainChild’s Core Series temperature controllers. With a user-friendly interface, it allows engineers and technicians to configure parameters, copy settings between devices, and perform firmware upgrades via USB connection. The software supports offline setup and can store multiple configuration files, making it ideal for OEM production lines, system integrators, and field engineers.

Batch Read/Write for Multiple Controllers 

BC-SET allows users to connect multiple controllers of the same model and perform batch parameter read/write by defining a node address range. This feature significantly streamlines configuration in OEM or multi-device environments.

Clear and Accessible System Menu 

The system menu offers quick access to key operations like Rescan (F5), Read Data (F6), Write Data (F7), Write Multiple (F8), and Communication Settings (F9). Built-in hotkeys support fast, efficient navigation.

Intuitive Communication Setup Interface  

The communication settings window lets users define COM port, baud rate, parity, data bits, and stop bits — with a “Default” button for quick reset and “Save and Exit” to finalize setup. Designed to reduce setup errors.

Visual Profile Editor for Programmable Controllers 

For controllers with profile functionality, BC-SET provides a graphical editor to configure temperature ramp/soak segments. Users can easily read, modify, and write profile parameters for precise thermal process control.

Industrial-Grade Protection with Global Compliance

IP30 front panel, IP20 terminals, UL / CE / RoHS approved

The L91 front panel is designed with an IP30 protection rating, providing a barrier against dust and accidental contact in indoor environments. When terminal covers are installed, the rear housing meets IP20 standards. This ensures safe integration into industrial control cabinets or panels. Certified under FM, UL, cUL, CE, RoHS, and REACH standards, the L91 meets global safety and EMC requirements. The flame-retardant polycarbonate housing enhances durability, making it suitable for long-term applications in demanding industrial settings.

Applications

Specification

 Mounting Diagram


 Power

Power Supply

90 ~ 250 VAC, 47 ~ 63 Hz, 11 ~ 26 V AC/VDC, SELV, Limited Energy

Power Consumption

10VA, 5W Maximum

Over Voltage Category

II
 Signal Input

Type

Thermocouple: J, K, T, E, B, R, S, N, L; RTD: PT100 DIN, PT100 JIS; mV: 0 ~ 60 mV; Current: 0 ~ 20mA; Voltage: 0 ~ 1 V, 0 ~ 10V

Resolution

18 Bits

Sampling Rate

5 Times / Second (200msec)

Input characteristics

Type

Range

 Accuracy@ 25 °C

Input Impedance

J

-120 ~ 1000 °C (-184 ~ 1832 °F)

±2 °C

2.2MΩ

K

-200 ~ 1370 °C (-328 ~ 2498°F)

±2 °C

2.2MΩ

T

-250 ~ 400°C (-418 ~ 752°F)

±2 °C

2.2MΩ

E

-100 ~ 900 °C (-148 ~ 1652 °F)

±2 °C

2.2MΩ

B

0 ~ 1820 °C (32 ~ 3272 °F)

±2 °C (200°C - 1800°C)

2.2MΩ

R

0 ~ 1767.8 °C (32 ~ 3214 °F)

±2 °C

2.2MΩ

S

0 ~ 1767.8 °C (32 ~ 3214 °F)

±2 °C

2.2MΩ

N

-250 ~ 1300 °C (-418 ~ 2372 °F)

±2 °C

2.2MΩ

L

-200 ~ 900 °C (-328 ~ 1652 °F)

±2 °C

2.2MΩ

PT100 (DIN)

-210 ~ 700 °C (-346 ~ 1292 °F)

±0.4°C

1.3KΩ

PT100 (JIS)

-200 ~ 600 °C (-328 ~ 1112 °F)

±0.4°C

1.3KΩ

mV

-8 ~ 70mV

±0.05%

2.2MΩ

mA

-3 ~ 27mA

±0.05%

100Ω

VDC

-1.3 ~ 11.5VDC

±0.05%

510KΩ

Temperature Effect

1.5μV /° C

Sensor Lead Resistance Effect

T/C: 0.2uV/ohm; 3-wire RTD: 2.6 °C/ohm of resistance difference of two leads; 2-wire RTD: 2.6 °C/ohm of resistance sum of two leads 200nA

Burn-out Current

200nA

Common Mode Rejection Ratio(CMRR)

120 dB

Normal Mode Rejection Ratio (NMRR)

55dB

Sensor Break Detection

Sensor open for TC, RTD and mV inputs, below 1 mA for 4 ~ 20 mA input, below 0.25V for 1 ~ 5 V input.

Sensor Break Responding Time

Within 4 seconds for TC, RTD and mV inputs, 0.1 second for 4 ~ 20 mA and 1 ~ 5 V inputs.
Output 1  / Output 2

Relay Rating

2A / 240 VAC, life cycles 200,000 for resistive load

Pulsed Voltage

Source Voltage 5V, current limiting resistance 66 Ω

Triac ( SSR ) Output

Rating

1A / 240 VAC

Inrush Current

20A for 1 cycle

Min. Load Current

50 mA rms

Max. Off-state Leakage

3 mA rms

Max. On-state Voltage

1.5V rms

Insulation Resistance

1000 Mohms min. at 500 VDC

Dielectric Strength

2500 VAC for 1 minute

Limit Control Function

High Limit, Low limit and High / L ow Limit programmable

Alarm Function

Process Value High, Process Value Low

Alarm Mode

Normal, Latching
Transmitter Power Supply (Output 2)

Transmitter Power
Supply Output
Characteristics

Type

Tolerance

Maximum Output Current

Ripple Voltage

Isolation Barrier

20V

± 1V

25mA

0.2Vp-p

500 VAC

12V

± 0.6V

40mA

0.1Vp-p

500 VAC

5V

± 0.25V

80mA

0.05Vp-p

500 VAC
Digital Filter

Function

First Order

Time Constant

0,0.2, 0.5, 1, 2, 5, 10, 20, 30, 60 Seconds Programmable
 Event Input

Logic Low

-10V minimum, 0.8V maximum.

Logic High

2V minimum, 10V maximum

Functions

Remote reset, remote lockout.
 Data Communication

Interface

RS-485 or RS-232

Protocol

Modbus RTU (Slave Mode)

Address

1 ~ 247

Baudrate

2.8KBPS ~ 115.2 KBPS

Parity Bit

None, Even or Odd

Stop Bit

1 or 2 Bits

Data  Length

7 or 8 Bits

Communication Buffer

50 Bytes
Analog Retransmission

Output Signal

4 ~ 20mA, 0 ~ 20 mA, 0 ~ 10VDC, 0 ~ 5VDC, 1 ~ 5VDC

Resolution

15 Bits

Accuracy

±0.05% of Span ± 0.0025% / °C

Load Resistance

0 to 500Ω for Current Output , 10KΩ minimum for Voltage Output

Output Regulation

0.01% for full load change

Output Setting Time

0.1 Second (Stable to 99.9%)

Isolation Breakdown

1000 VAC minimum

Integral Linearity Error

±0.005% of Span

Temperature Effect

±0.0025% of Span /°C

Saturation Low

0mA or 0VDC

Saturation High

22.2mA or 5.55V, 11.1V min

Linear Output Ranges

0 ~ 22.2mA (0 ~ 20mA / 4 ~ 20mA), 0 ~ 5.55VDC (0 ~ 5VDC / 1 ~ 5 VDC), 0 ~ 11.1VDC (0 ~ 10VDC)

User Interface

Keypad

4 Keys

Display Type

4 Digit LCD Display

No. of Display

1

Upper Display Size

0.4”(10mm)

Lower Display Size

N.A.

Programming Port

For automatic setup, calibration and testing

Communication Port

Connection to PC for supervisory control
 Environmental and Physical Specifications

Operating Temperature

-10°C ~ 50°C

Storage Temperature

-40°C ~ 60°C

Humidity

0 ~ 90 % RH (Non-Condensing)

Altitude

2000 Meters maximum

Pollution

Degree II

Insulation Resistance

20 MΩ minimum (@500 VDC)

Dielectric Strength

2000 VAC, 50 / 60 Hz for 1 Minute

Vibration Resistance

10 ~ 55 Hz , 10m / s² for 2 Hours

Shock Resistance

200 m / s² (20g)

Housing

Flame Retardant Polycarbonate

Mounting

Panel Mounting
DIN Size
1/16

Dimensions (W*H*D) (mm)

48*48*94

Depth Behind Panel (mm)

86

Cut Out Dimensions (mm)

45*45

Weight (grams)

150
Approval Standards

Safety

FM, UL, cUL, CE, R oHS, REACH

Protective Class

IP30 front panel, indoor use, IP20 housing and terminals (with protective cover).

EMC

EN61326

Download

SelectSeries_L41&L91_Catalog_V1.02_EN

SelectSeries_L41&L91_Catalog_V1.01_CH
SelectSeries_L91_UserManual_UM0L911E_EN

Software_BC_Set_2.0
Software_BC_Set_Pro_V1.1.0.12_2.0(above V22)

Data_Logger_Firmware_XH10_v1.1.0.34​

Software_BC_Set_Pro_V1.1.0.12_2.0​
Software_DAQ_V2.73(2501)*1-hour trial only

Training_Demo_Data_Acquistion_Studio

UMEIO01A​
UMEIO01A​

IO_Brouchure_Ver.1.4/

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FAQ

The L91 accepts thermocouples (J, K, T, E, B, R, S, N, L), RTD sensors (PT100 DIN/JIS), low-voltage signals (0–60mV), voltage (0–1V, 0–10V), and current (0–20mA). All input types are selectable through the panel or software. With 18-bit resolution and 5 samples/sec rate, it delivers high accuracy and fast response.

The L91 features a programming port that works with the CC91-2 communication cable and BC-Set PRO software. This allows users to clone settings, update firmware, and calibrate devices via PC, simplifying mass deployment in OEM environments.

Yes, the L91 supports RS-485 via the optional CM96-1 module. It uses the Modbus RTU protocol and is compatible with SCADA systems. Once installed, users can read/write parameters and remotely configure the unit.

L91 offers high, low, deviation, and latching alarms. It also supports remote reset and lockout via digital input. Alarms can trigger relay outputs or be monitored through the panel or communication port.

What certifications and protections does the L91 have?

The L91 is certified to UL61010, CE, RoHS, and REACH standards. The front panel is IP30-rated, and the rear terminal block is IP20 when covered. It’s designed for panel mounting in industrial control environments.  

Ordering Code

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