How to differentiate power consumption & power dissipation？

And the Power dissipation is "lost" or wasted power, represented by the power converted to lower forms such as heat that are no longer useful in that system. 

In relation to a Power Supply the dissipated power is the difference between the input and the output power, as the rest is wasted or dissipated. So power dissipation is not fixed for these hardware but what we can say is it will be approx. 10% of Power consumption on full load. 

The power Consumption in VA is Bus Current * Voltage

Typical power consumption is 7mA at nominal supply 24 VDC from External power supply  
When all inputs are ON, current drawn on internal 5VDC bus is 40 mA 

=> For External power supply , power consumption is (24 VDC x 0.007 A) = 0.168 Watts ( not 1.68) : this value is so low we can nearly forget it when sizing the 24v external power supply  

For 5VDC internal Power Supplies, power consumption is (5VDC x 0.04) = 0.2 Watts; yes but this characteristic is not so important, as the 5V is provided internally by the PLC itself , and as this module has very low consumption within 5V, this create never a problem to have this module into the TM3 configuration ( from 5V point of view)