Module Outputs - 1756-HSC

The 1756-HSC module has 4 outputs, isolated in pairs (0&1, 2&3). Each output is capable of sourcing current from an externally supplied voltage up to 30V dc. You must connect an external power supply to each of the output pairs. The outputs can source 1A dc and are hardware-driven. They turn ON or OFF in less than 50ms when the appropriate count value has been reached.

Controlling the ON/OFF Output Status

Each output on the 1756-HSC module can be turned ON and OFF at your own discretion. The operation of output(s) tied to a counter are performed independently from the controller scans.

For example, a 1756-HSC module can be programmed to turn ON an output when the count value reaches 2000, and keep the output ON for 3000 counts. In this case, the ON value must be programmed for 2000 counts and the OFF value must be programmed for 5000 counts.

Up to two ON-OFF windows may be used for each output.

These windows can be overlapped as part of a leading edge advance operation. In this case, the output’s conditions maintain the ON condition of either window.

Manual Override of Outputs

Outputs may be turned ON or OFF by a ladder logic application.

Assigning Outputs to Counters

By setting configuration data, you can assign the outputs on the module to any of the various counters. You can assign as many as 2 outputs to a given counter. However, an output may be assigned only once to a counter; it is not possible to use the same output with 2 different counters.

Operation of Outputs

When the outputs for the 1756-HSC module are enabled and assigned to a counter, they operate in an ON-OFF fashion.

For example, assume that the module was programmed to turn ON an output when a count value of 2000 was reached. Further, assume that the user desired to have the output remain energized for a period of 3000 counts and then turn OFF. The end result would be that the outputs would turn ON at count of 2000, would remain energized for a period of 3000 additional counts, and would turn OFF at 5000 counts. The ON and OFF values are circular around zero.

In the rate measurement mode, the ON and OFF values associated with each output represent a frequency value instead of a count value. The maximum frequency value which may be entered in an ON or OFF value is 500KHz.

Tying Outputs to Counters

You can jumper any of the outputs to any of the counter inputs on the module’s RTB. In this way, it is possible to use the outputs to reset a counter or to cascade counters. If using the outputs this way, make certain that the correct input terminals are used to interface with the appropriate output voltage.

Hysteresis

The 1756-HSC module contains a fixed hysteresis of +/- 1 count, based on the encoder. The module will operate in reverse if moved backward in rotation.