Specifications
Publication 1794-SG002D-EN-P - May 2012
Select FLEX I/O Modules 61
1794-VHSC 2 Channel Very High Speed Counter Module
A counter module has two incremental quadrature encoder interfaces each with
three inputs (A, B, and Z). Each input module has ± inputs for connection to
pulse transmitters with complementary or non-complementary signals.
The counter can count pulses of one or two pulse trains for up/down counting
and detection of a selectable number of edges (X1, X2, X4). Each of the two
counters has an upper limit of 1MHz, a 24-bit counter register, a preset register,
and a latch register.
Power to the module is supplied from an external 24V power supply. The
1794-VHSC has two outputs that can be configured for overlapping, multiple
windows, and/or pulse width modulation.
Dimensions (HxWxD), approx 46 x 94 x 53 mm (1.8 x 3.7 x 3.1 in.)
94 x 94 x 69 mm (3.7 x 3.7 x 2.7 in.) installed
Temperature, operating 1794-IJ2: 0…55 °C (32…131 °F)
1794-IJ2XT: -20…70 °C (-4…185 °F)
(1) Current Limited: All outputs can be on simultaneously without derating.
2 Channel Very High Speed Counter Module
Specification 1794-VHSC
Input groups 2 groups of A/A, B/B, and Z/Z pairs with 5V DC or
15…24V DC terminations
Input frequency, max 1.0 MHz counter and encoder X1 (no filters)
500 kHz encoder X2 (no filters)
250 kHz encoder X4 (no filters)
Voltage, on-state input, min 5V DC terminations: >2.6V DC
15…24V DC terminations: >12.5V DC
Voltage, on-state input, max 5V DC terminations: ±6V
15…24V DC terminations: Refer to derating curve
Voltage, off-state input, min 5V DC terminations: ≤ 1.25V DC
15…24V DC terminations: ≤ 1.8V DC
Current, on-state input, min >5 mA
Current, on-state input, max ≤ 0.250 mA
Input filter selections 5: Off, 10 μs, 100 μs, 1.0 ms, 10.0 ms per A/B/Z group
Output control Outputs can be tied to 8 compare windows
Output supply voltage range 5…7V DC or 10…31V DC
Leakage current, off-state output,
max
≤ 0.3 mA
Voltage drop, on-state output,
max
5V operation – 0.5 A
12…24V operation – 1.0 A
24V DC Input Frequency Module
Specification 1794-IJ2, 1794-IJ2XT