PRODUCT INFORMATION
Product Overview
The Allen-Bradley 1794-VHSC is a FLEX I/O Very High Speed Counter Module. It provides high-speed counting capabilities for demanding industrial automation applications. The hardware features two input channels with two counters per input channel. It supports three encoder modes with counting frequencies reaching up to 1 MHz. Terminal base terminations support either 5V DC or 15 to 24V DC operation.
The module includes two isolated output groups rated for 0.5A at 5V DC. These outputs also support switching up to 1.0A at 12 to 24V DC. Backplane logic current draw is 75 mA at 5V DC via the Flexbus. An external 24V DC nominal power supply powers the module across 19.2 to 31.2V DC. Installation requires mounting on a 1794-TB3G or 1794-TB3GS base with keyswitch position 1.
TECHNICAL DATA
Technical Specifications
| Parameter | Specification |
|---|
| Product Line | Flex I/O 1794 |
|---|
| UPC | 612598205493 |
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| Weight | 0.56 lbs (0.26 kg) |
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| Input Channels | 2 |
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| Inputs per Counter | 2 Groups of 3 |
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| Input Voltage | 5V DC |
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| Input Off-state Voltage | <1.8V DC |
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| Input Off-state Current | <0.25 mA |
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| Input On-state Current | >5mA |
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| Outputs | 2 Isolated Groups of 2 |
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| Output Supply Voltage Range | 10-31V DC |
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| Power Dissipation | 5.0W @ 31.2V DC max. |
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| Thermal Dissipation | 17.1 BTU/hr. @ 31.2V DC max. |
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TECHNICAL INFORMATION
Features
- Two input channels supporting high-speed counting frequencies up to 1 MHz.
- Configurable operation supporting three distinct encoder modes.
- Selectable input terminations for 5V DC or 15 to 24V DC signals.
- Two isolated output groups rated at 0.5A at 5V DC and 1.0A at 12 to 24V DC.
- Basic insulation providing 50V isolation between six separate circuit areas.
- Flexbus logic power consumption of 75 mA at 5V DC.
TECHNICAL INFORMATION
Applications
- High-speed pulse counting and frequency tracking in industrial automation systems.
- Motion feedback processing using incremental encoder signals.
- Fast event counting with direct isolated output switching.
TECHNICAL INFORMATION
Connections / Interfaces
- Connects to field devices through a 1794-TB3G or 1794-TB3GS terminal base unit.
- Flexbus interface provides backplane communication and logic power.
- Wiring points accommodate 5V DC or 15 to 24V DC termination options.
TECHNICAL INFORMATION
Installation Guidelines
- Mount the module directly onto a 1794-TB3G or 1794-TB3GS terminal base unit.
- Set the terminal base keyswitch to position 1 before installing the unit.
- Supply external 24V DC power within the allowable 19.2 to 31.2V DC range.
- Maintain ambient operating temperatures between 0 and 55 degrees Celsius.
TECHNICAL INFORMATION
Configuration Guidelines
- Configure the module for one of three supported encoder modes.
- Select terminal base wiring according to 5V DC or 15 to 24V DC field requirements.
TECHNICAL INFORMATION
Compatibility
- Mounts on Allen-Bradley 1794-TB3G and 1794-TB3GS terminal base units.
- Provides counter signals to compatible programmable controllers with EtherNet capability.
TECHNICAL RESOURCES
Documentation
COMPATIBILITY
Compatibility & Replacement
COMPATIBLE MODELSMounts on Allen-Bradley 1794-TB3G and 1794-TB3GS terminal base units. Provides counter signals to compatible programmable controllers with EtherNet capability.
Verify compatibility against the exact Part Number, revision and manufacturer documentation before ordering.
PART VERIFICATION
Before You Order
Industrial automation parts can share similar model names, suffixes and revisions. Confirm the complete manufacturer Part Number before purchase.
01Check Part NumberMatch the complete ordering code on the existing unit.
02Confirm RevisionCheck suffix, hardware or firmware when applicable.
03Send a Label PhotoWe can review a clear label photo when identification is uncertain.
ORDERING PROCESS
From RFQ to Dispatch
1Submit Part Number2Verify Product Identity3Confirm Stock & Condition4Issue Quotation5Dispatch & Tracking
PRODUCT FAQ
Frequently Asked Questions
What is the maximum input counting frequency of the 1794-VHSC?
The 1794-VHSC supports input frequencies up to 1 MHz for high-speed pulse processing.
Which terminal bases are compatible with the 1794-VHSC module?
The module mounts onto Allen-Bradley 1794-TB3G or 1794-TB3GS terminal base units.
What keyswitch position is needed on the terminal base?
Set the terminal base keyswitch to position 1 before inserting the module.
What external power supply does the 1794-VHSC require?
It requires an external 24V DC nominal power supply operating between 19.2 and 31.2V DC.
