The Banner Engineering SD50 is an industrial text display with side mounted, multicolor indicator LEDs. This display is a natural extension of a Programmable Logic Controller (PLC) providing high contrast text and colored alarm indicators as shown in Figure 1.
There are three models associated with the Banner SD50 line including:
This engineering brief is focused on the discrete module with a bias toward small PLC applications. Technically, the featured display is a demo model (DK-SD50), however, the article content will carry over to Banner’s discrete control model SD50P300WD15QP.
This article is part of the DigiKey Field Guide for Industrial Automation
Location: Start It → Displays
Difficulty: 
Engineer — difficulty levels explained
Author: Aaron Dahlen | MSEE | Senior Applications Engineer, DigiKey
Last update: 06 Mar 2026
Figure 1: Image of the Banner SD50 display surrounded by the PRO-KIT programmer (sold separately).
What functions are performed by the SD50?
The SD50 display operates in two general modes including text and bar graph mode, or a combination of the two. Video 1 presents a mixed bar graph and text display for an interactive Tank Level Indicator (TLI) application. Note that the display includes side-mounted indicator LEDs. These may be programmed to change color as shown at video time index 2:30 with results shown at 3:10.
Video 1: Demonstration of the Banner SD50 and radar when used together for a TLI application.
Tech Tip: When using the PWM-based bar graph, be sure to activate the filter and hysteresis. This will prevent objectionable bouncing between states.
How to program the SD50 display
The Banner SD50 is closely related to other Banner products such as the K50 multicolor Touch Button. Products within this ecosystem share a common programming language and interface. Banner’s Pro Editor is freely available for download while the PRO-KIT programmer must be purchased separately. Note that the SD50 display in Figure 1 is flanked by the PRO-KIT components.
The Banner software is very easy to use. Please refer to the K50 multicolor Touch Button document for a brief introduction.
How to connect the discrete controlled SD50 to a PLC
This is where the Banner Engineering team truly shines. They provide several different ways to interface the display to a small PLC including:
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Discrete control with a 4-wire interface. This allows any random access to any message previously stored in the SD50.
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Sequence control with a 2-wire reset and step function. This is ideal for machines with predictive sequences such as insert part, feeding, clamping, drilling, ejecting, remove part. The reset wire allows the PLC to jump to the starting position.
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Pulse Width Modulation (PWM) control with a single wire. Random access to all stored messages.
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Pulse Frequency Modulation (PFM) control with a single wire for PLCs with the ability to change PWM frequency on the fly. Random access to all stored messages.
In Figure 2 we see the display controlled by a Crouzet 88983902 PLC. This Millenium Slim PLC is among the smallest PLC offered by DigiKey. With only one wires, the Crouzet PLC is able to step between 15 unique text messages. With a single PWM output, this tiny PLC could also control the TLI bar graph as shown in Video 1.
Figure 2: The Banner SD50 is controlled by an ultra-compact Crouzet Millenium Slim PLC.
Parting thoughts
The Banner SD50 fits within the Banner Pro ecosystem using the same tools and techniques as other devices such as the K50 multicolor Touch Button. Multiple control methods simplify wiring and control. This flexibility extends to the ultra-compact PLCs such as the Crouzet Slim featured in this article.
Best wishes,
APDahlen
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About This Author
Aaron Dahlen, LCDR USCG (Ret.), is a Senior Applications Engineer at DigiKey in Thief River Falls. His background in electronics and industrial automation was shaped by a 27-year military career as both technician and engineer, followed by over a decade of teaching.
Dahlen holds an MSEE from Minnesota State University, Mankato. He has taught in an ABET-accredited electrical engineering program, served as coordinator of an electronic engineering technology program, and instructed military technicians in component-level repair.
Today, he has returned to his home in northern Minnesota, completing a decades-long journey that began with a search for capacitors. Read his story here.