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Revisions: Ser A

Description:   The Allen-Bradley 1794-VHSC Flex I/O Very High Speed Counter Module has 2 Input Channels, 2 Groups of 3 Inputs per Counter, and a 5V DC Input Voltage. It also operates with a <0.25 mA Input Off-state Current and a >5mA Input On-state Current.

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About 1794-VHSC

The 1794-VHSC Flex I/O High-Speed Counter by Allen-Bradley is an intelligent I/O module which performs high-speed counting for most industrial applications and provides signals to all compatible programmable controller with EtherNet capability. The module has 2 input channels, with 2 counters per input channel, configured for 3 encoder modes with 5V DC or 15-24V DC terminations. The 1794-VHSC has an input rating of 5V DC or 15-24V DC (depending on the terminal base’s termination) and an input current of 19.1mA at 5V DC and 25.7mA at 6V DC using a 5V DC termination. It also has an input current of 6.1mA at 15V DC and 10.2mA at 24V DC with 15-24V DC termination, and an OFF-state voltage of <1.25V DC and <1.8V DC with 5V DC termination and 15-24V DC termination. The 1794-VHSC also has a counter-dependent input OFF-state and ON-state ratings and its input frequency can get to 1MHz. It has 2 isolated outputs (with 2 groups) with an electrical rating 0.5A at 5V DC and 1.0A at 12-24V DC. 
The 1794-VHSC’s outputs have an output supply voltage range of 5-7V DC and 10-31V DC, with a leakage current of less than 300μA in its OFF state, and a voltage loss of 0.9V DC at 0.5A with 5V DC termination and 0.9V DC at 1.0A with 12-24V DC termination. The 1794-VHSC is installed on either the 1794-TB3G or 1794-TB3GS terminal base unit and uses a 24V DC nominal external power supply with a supply range of 19.2-31.2V DC with a current of 100mA at 24V DC. It has 1 key-switch position and provides 50V isolation using basic insulation type between 6 isolated areas tested at 850V DC for 1s. The 1794-VHSC has a Flexbus current of 75mA at 5V DC and dissipates 5W heat at 31.2V DC. Its operational temperature ranges between 0 and 55 °C (32 and 131 °F) at 5-95% humidity condition and the module has dimensions of 3.7in x 3.7in x 2.7in with the module installed.

Technical specifications:

Part Number:1794-VHSC
Product Type:Flex I/O Very High Speed Counter Module
Input Channels:2
Inputs per Counter:2 Groups of 3
Input Voltage:5V DC
Input Off-state Voltage:<1.8V DC
Input Off-state Current:<0.25 mA
Input On-state Current:>5mA
Outputs :2 Isolated Groups of 2
Output Supply Voltage Range:10-31V DC
Power Dissipation:5.0W @ 31.2V DC max.
Thermal Dissipation:17.1 BTU/hr. @ 31.2V DC max.

Please refer to the manual for more information about the 1794-VHSC such as the wiring diagrams, data sheets, firmware information and migration or obsolescence details.

Revision Part # Also Known as Availability
1794-VHSC Ser A
1794-VHSC/A, Series A, Rev A Request Quote

Common misspellings: 1794VHSC
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