Implementing 3-Switch XOR Ladder Logic with Internal Bit
Implement a 3-SPST switch XOR light circuit in LogixPro or RSLogix 500 using an internal relay bit. Includes truth tables, boolean equations, and verified.
Processing 24 V HTL encoder signals with absolute precision, the Beckhoff EL5151-0021 serves as a high-performance incremental encoder interface within the modular EtherCAT Terminal system. This single-channel EtherCAT Terminal is specifically engineered to interface directly with incremental encoders, enabling accurate position and velocity tracking in dynamic industrial automation systems. By utilizing phase-shifted signals, the module handles complex motion profiles with ease.
The unit features integrated latch and gate inputs for rapid registration of encoder values based on external hardware events. Additionally, a dedicated 24 V DC digital output is available, permitting onboard hardware-level comparison and workpiece measurement functions. Its robust design, status LEDs, and compact form factor make it an essential component for high-reliability machine controls requiring rapid I/O processing.
| Manufacturer | Beckhoff |
| Part Number | EL5151-0021 |
| Product Type | EtherCAT Terminal |
| Number of Channels | 1 |
| Technology | Incremental encoder interface (HTL, 24 V DC) |
| Encoder Connection | 1 x A, B, C (24 V DC, single-ended, EN 61131-2, Type 1) |
| Input Voltage Levels | "0": less than 5 V DC, "1": greater than 15 V DC (typ. 5 mA) |
| Additional Inputs | 1 x Latch input (24 V DC) |
| Additional Outputs | 1 x Digital output (24 V DC, 0.5 A) |
| Encoder Operating Voltage | 24 V DC (-15% / +20%, generated from the 24 V DC power contacts) |
| Counter Range | 1 x 32 bit |
| Limit Frequency | 400,000 increments/s (with 4-fold evaluation), equivalent to 100 kHz |
| Quadrature Decoder | 4-fold evaluation |
| Nominal Voltage | 24 V DC (-15% / +20%) |
| Current Consumption (Power Contacts) | typ. 100 mA + load |
| Max. Current Load Power Contacts | 10 A |
| Special Features | Latch function, parameterizable output 24 V DC (compare function), workpiece measurement |
| Operating Temperature | 0 to +55 degC |
| Storage Temperature | -25 to +85 degC |
| Relative Humidity | 95%, no condensation |
| Vibration and Shock Resistance | Conforms to EN 60068-2-6 / EN 60068-2-27 |
| EMC Immunity and Emission | Conforms to EN 61000-6-2 / EN 61000-6-4 |
| Protection Rating | IP20 |
| Housing Material | Polycarbonate |
| Installation | 35 mm DIN rail (EN 60715) with locking tab |
| Side-by-Side Mounting | Double slot and key connection |
| Wiring Connection | Spring actuation by screwdriver |
| Solid/Stranded Wire Connection Cross-Section | 0.08 to 2.5 mm² (AWG 28...14) |
| Ferrule Wire Connection Cross-Section | 0.14 to 1.5 mm² (AWG 26...16) |
| Stripping Length | 8 to 9 mm |
| Dimensions (W x H x D) | 12 mm x 100 mm x 68 mm |
| Weight | approx. 50 g |
Global Express Shipping
Returns & Warranty

Processing 24 V HTL encoder signals with absolute precision, the Beckhoff EL5151-0021 serves as a high-performance incremental encoder interface within the modular EtherCAT Terminal system. This single-channel EtherCAT Terminal is specifically engineered to interface directly with incremental encoders, enabling accurate position and velocity tracking in dynamic industrial automation systems. By utilizing phase-shifted signals, the module handles complex motion profiles with ease.
The unit features integrated latch and gate inputs for rapid registration of encoder values based on external hardware events. Additionally, a dedicated 24 V DC digital output is available, permitting onboard hardware-level comparison and workpiece measurement functions. Its robust design, status LEDs, and compact form factor make it an essential component for high-reliability machine controls requiring rapid I/O processing.
| Manufacturer | Beckhoff |
| Part Number | EL5151-0021 |
| Product Type | EtherCAT Terminal |
| Number of Channels | 1 |
| Technology | Incremental encoder interface (HTL, 24 V DC) |
| Encoder Connection | 1 x A, B, C (24 V DC, single-ended, EN 61131-2, Type 1) |
| Input Voltage Levels | "0": less than 5 V DC, "1": greater than 15 V DC (typ. 5 mA) |
| Additional Inputs | 1 x Latch input (24 V DC) |
| Additional Outputs | 1 x Digital output (24 V DC, 0.5 A) |
| Encoder Operating Voltage | 24 V DC (-15% / +20%, generated from the 24 V DC power contacts) |
| Counter Range | 1 x 32 bit |
| Limit Frequency | 400,000 increments/s (with 4-fold evaluation), equivalent to 100 kHz |
| Quadrature Decoder | 4-fold evaluation |
| Nominal Voltage | 24 V DC (-15% / +20%) |
| Current Consumption (Power Contacts) | typ. 100 mA + load |
| Max. Current Load Power Contacts | 10 A |
| Special Features | Latch function, parameterizable output 24 V DC (compare function), workpiece measurement |
| Operating Temperature | 0 to +55 degC |
| Storage Temperature | -25 to +85 degC |
| Relative Humidity | 95%, no condensation |
| Vibration and Shock Resistance | Conforms to EN 60068-2-6 / EN 60068-2-27 |
| EMC Immunity and Emission | Conforms to EN 61000-6-2 / EN 61000-6-4 |
| Protection Rating | IP20 |
| Housing Material | Polycarbonate |
| Installation | 35 mm DIN rail (EN 60715) with locking tab |
| Side-by-Side Mounting | Double slot and key connection |
| Wiring Connection | Spring actuation by screwdriver |
| Solid/Stranded Wire Connection Cross-Section | 0.08 to 2.5 mm² (AWG 28...14) |
| Ferrule Wire Connection Cross-Section | 0.14 to 1.5 mm² (AWG 26...16) |
| Stripping Length | 8 to 9 mm |
| Dimensions (W x H x D) | 12 mm x 100 mm x 68 mm |
| Weight | approx. 50 g |
Global Express Shipping
Returns & Warranty
Orders are processed and delivered Monday-Friday (excluding public holidays).
For full eligibility, restocking fees, and international return details, please view our official Refund & Return Policy .
| Country of origin |
Germany
|