5 Function blocks
5.27 PW, pulse width modulation
Control Relay easy800 11/11 MN04902001Z-EN www.eaton.com 239
The function block causes a direct output of the pulse to the corresponding
device output (Q1 and Q2).
The following applies to the minimum on duration:
• Minimum on time = minimum off time = ME
• ME
1ms
• ME 10 % PD
• If the actual value of the pulse width is less than ME, the output stays at
0 and the contact E1 closes.
• If the off time of the pulse at the output is less than ME, the output stays
at 1, Q1 or Q2 are in continuous operation. The contact E1 closes.
• If ME stays at 0 or is not connected, ME is preset to 0.1 ms.
Figure 174:Pulse width modulation signal diagram
EN: Enable coil
SV: Manipulated variable
ME: Minimum on time or minimum off time
E1: Error in indication contact
Q1/2: Pulse sequence at the device output Q1 and/or Q2
￫
The ratio of period duration/minimum on duration (P/M)
determines which percentage of the manipulated variable has
no effect. The minimum on duration must be set as low as
possible so that the P/M ratio is as high as possible. If the
minimum on duration must not be too low, due to the output
relay, the period duration must be increased accordingly.
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