I. Core Specifications (Official Parameters)

Table

Item Detailed Parameters
Model
1794-VHSC
Channels
2 Independent High-Speed ​​Counting Channels
Maximum Counting Frequency
Single-ended (TTL/5V): 1 MHz; Differential (RS-422): 250 kHz (X4 multiplier)
Counting Capability
32-bit counter (0 ~ 16,777,215); supports up/down, quadrature, preset/wind-back
Input Signals
Single-ended 5V TTL / Differential RS-422; configurable 5V or 15–24V termination
Outputs
4 isolated source outputs (2 groups); 5–24V DC, maximum 1 A per channel
Power Supply
Flexbus 5V + external 24V DC (input/output); can operate independently of Flexbus after configuration
Communication
Ethernet configuration, compatible with CompactLogix / ControlLogix
Physical
DIN DIN rail mounting; dimensions approx. 76×51×102 mm; net weight approx. 0.1 kg
Environment: 0–60°C; IP20 open type; UL/CSA/CE/ATEX certified
Lifecycle: Active Mature (Mature and in production, repairable)
II. Main Functions and Modes

• Counting/Encoder Mode: Supports A/B phase quadrature, X1/X2/X4 frequency multiplication, used for position/speed feedback

• Period/Speed ​​Measurement: Direct output of frequency, speed, and accumulated pulse

• PWM Output: Programmable pulse width modulation, triggered by a counting window

• Interrupt and Safety: Interrupt triggered by a count value threshold; output can enter a safety state in case of network failure
III. Selection and Usage Considerations

1. Base Compatibility: Must be used with 1794-TBx/TBS series terminal blocks; size/weight varies depending on the base.

2. Input Configuration: Differential input is recommended with a 120Ω terminating resistor; single-ended 5V and 24V. 3. Output Isolation: Two sets of independently isolated outputs, with a total current of ≤ 2 A for each set.

4. Software Configuration: Configured via Studio 5000 / RSLogix 5000; firmware D and above support frequency enhancement.