Siemens 420 manual Parameterizations

Issue 07/04 3 Functions

Example:	The permanent PID controller should fulfill the following
	secondary conditions/limitations:
	PID controller enable and PID setpoint input via PID fixed
	frequencies and PID actual value via the analog input.
	Parameterizations:
	a. Permanent PID controller enable:	P2200	= 1.0
	b. Setpoint input via PID-FF:	P2253	= 2224
	c. Actual value input via analog input ADC:	P2264	= 755

The supplementary (additional) setpoint is added to the main setpoint (PID-SUM) and the sum is fed to the setpoint filter (PID-PT1) at the setpoint-actual value summation point via the PID ramp-function generator (PID-RFG). The source of the supplementary setpoint (BICO parameter P2254), the ramp-up / ramp-down times of the PID ramp-function generator (P2257, P2258) as well as also the filter time (P2261) can be adapted to the particular application by appropriately parameterizing the corresponding parameters.

Similar to the PID setpoint branch, the actual value branch of the technological controller has a filter (PID-PT1) which can be set using parameter P2265. In addition to the smoothing, the actual value can be modified using a scaling unit (PID-SCL).

The technological controller can be parameterized as either P, I or PI controller using parameters P2280 and P2285.

					P2293
				P2291
				P2280 P2285
				Kp	Tn	y
PID				+		x	Motor
setpoint				-			control
		r2262		r2273			r2294
	P2267	y		P2292
PID
			x	r2272
feedback
	P2268				P2293
Fig. 3-37	PID controller

For specific applications, the PID output quantity can be limited to defined values. This can be achieved using the fixed limits - P2291 and P2292. In order to prevent the PID controller output exercising large steps at power-on, these PID output limits are ramped-up with ramp time P2293 from 0 to the corresponding value P2291 (upper limit for the PID output) and P2292 (lower limit for the PID output). As soon as these limits have been reached, the dynamic response of the PID controller is no longer limited by this ramp-up/ramp-down time (P2293).

MICROMASTER 420	Operating Instructions
6SE6400-5AA00-0BP0	107