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APPLICATION NOTE AN3
USING THE SSRMAN-1P-HR-XSC WITH A PWM COMMAND

Revised 12/20/11

This application note is using the SSRMAN-1P-HR-XSC to interface to the logic output of a temperature controller. This provides a cost savings by eliminating the need for an analog output on the temperature controller.

Considerations for using the PWM input Version

If the PLC, temperature controller or computer providing the PWM signal has 24V drive and the SSRMAN-1P-HR-XSC dipswitches switches are set to 0-10V, full output of the SSRMAN-1P-HR-XSC will be obtained at a 42% ~ (10V/24V x100%) duty cycle so rescaling in the PLC software is required. If the PWM command is 5V TTL drive, all of the command dipswitches should be set to off.   

If the command is coming from the 5 volt SSR drive of a temperature / process controller, all of the command dipswitches should be set to off and a 1K resistor should be added in parallel with the command input. The output cycle time of the temperature / process controller should be set to as fast as possible (100 or 200mS max) and the soft change switch should be set to on. When using a slow speed PWM per the aforementioned, the module should be ordered with a soft change of at least 2 seconds (SSRMAN-1P-HR-2SC) to smooth the control output.

The output signal generated by PLCs and Process / Temperature controllers is either push pull (TTL), Isolated Transistor, open collector, or a high side driver. Note the drive configurations, wiring and the position of the 0-10V switch #3 shown below. Tying the PLC ground to the power ground on the 24V / 0V terminals may cause damage to the SSRMAN or the PLC.

TTL (5Volt Logic)

Isolated Transistor

Open Collector (Switch 3 set to on when PLC +V is 10V or more)

High Side Driver (Switch 3 set to on when PLC +V is 10V or more)