A-B 1771-VHSC

Very HighSpeedCounter Module (Cat. No. 1771VHSC Series B)

Module Description

The VHSC module performs high speed counting for industrial applications. The module is an intelligent block transfer I/O module that interfaces signals with any Allen-Bradley programmable controller that has block transfer capability.Block transfer programming moves module status data from the module's memory to a designated area in the processor data table. It also moves configuration words from the processor data table to the module memory.
The VHSC module is a single-slot module that does not require an external power supply. (Note: The outputs do require a power supply.) After scanning the inputs and updating the outputs, the input data is converted to a specified data type in a digital format to be transferred to the processor's data table on request. Command and configuration data is sent from the programmable controller data table to the module with a BTWinstruction.
Features of the Module
The VHSC module counts pulses from encoders (such as Allen-Bradley Bulletin 845H, K, F, P, E and L), pulse generators or mechanical limit switches, proximity switches, etc. and returns either a count or frequency in binary or BCD format.
The module's features include:
• 4 input channels configurable for encoder mode, counter mode, period/rate mode and continuous/rate mode
• 8 outputs, isolated in groups of 2
• outputs are current-sourcing at 5 to 24V dc (2A maximum per output)
• single-ended or differential inputs
• 2-phase encoder inputs up to a frequency of 250KHz
• single-phase counter inputs up to a frequency of 1MHz
• input voltage range of 5 to 24V dc
• returns in status either count or frequency in binary or BCD format
• input counts as high as 999,999
• up to 500KHz in period/rate or rate measurement frequency modes
• outputs can be tied to any counter
• each output has a user-selectable on-off value
• outputs can be tied back to an input for cascading
• automatic default configuration
• each counter has a user-selectable preset and rollover value
• period/rate w/periodic outputs and period/rate w/dynamic outputs can be used for totalization
The 1771-VHSC module operates in the following modes:
• counter mode
• encoder X1 mode
• encoder X4 mode
• period/rate mode
• rate measurement frequency mode
• continuous/rate mode

Using the Indicators forTroubleshooting

The active indicator is on when the module has successfully powered up. When an input indicator (A, B) is on, it indicates that the input is high. When the output indicator is on, it indicates that the module has commanded the output to be on. When a gate/reset indicator (G) is on, its input is high. Since that signal can be inverted, it does not indicate whether the signal on that terminal is necessarily logically true.

A troubleshooting chart is shown below.

Other models：1771-NT2 ，1771-OA ，1771-OAD ，1771-OB ，1771-OBN ，1771-OD ，1771-OD16 ，1771-ODD ，1771-OFE1 ，1771-OFE