Mode Switch
MAN_ON STEP3_ON ST2BI_ON
Three-step control FALSE TRUE Any
Two-step control with bipolar control range
(-100 % to +100 %)
FALSE FALSE TRUE
Two-step control with monopolar control
range (0 % ... 100 %)
FALSE FALSE FALSE
Manual mode TRUE Any Any
In the three-step control mode, the actuating signal can adopt three states. The values of
the binary output signals QPOS_P and QNEG_P are assigned to the statuses of the
actuator. The table shows the example of a temperature control:
Output signal Actuator
Heat Off Cool
QPOS_P TRUE FALSE FALSE
QNEG_P FALSE FALSE TRUE
Based on the input variable, a characteristic curve is used to calculate a pulse duration.
The form of the characteristic curve is defined by the minimum pulse or minimum break
time and the ratio factor. The normal value for the ratio factor is 1. The “doglegs” in the
curves are caused by the minimum pulse or minimum break times.
n Minimum Pulse or Minimum Break Time
A correctly assigned minimum pulse or minimum break time P_B_TM can prevent
short on/off times that reduce the working life of switching elements and actuators.
Small absolute values at the input variable LMN that could otherwise gen-
erate a pulse duration shorter than P_B_TM are suppressed. Large input
values that would generate a pulse duration longer than (PER_TM -
P_B_TM) are set to 100 % or -100 %.
The positive and negative pulse duration is calculated by multiplying the input variable (in
%) with the period time:
Three-Step Control
VIPA SPEED7
Standard
PID Control > FB 43 - PULSGEN - Pulse generation
HB00 | OPL_SP7 | Operation list | en | 18-30 851
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