Siemens S7-300 Installation And Operating Manual page 189

Improving current measuring precision at channels 0 through 3 of the analog input module
It is advisable to interconnect unused voltage inputs with the corresponding current input
when using channels 0 to 3 of SM 336; AI 6 x 13Bit for current measurements. See the
figure below. This measure improves precision by approx. 0.2%.
Figure 9-7
Figure 9-8
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
Improving current measuring precision at channels 0 through 3 using 2 DMU
Improving current measuring precision at channels 0 through 3 using 4 DMU
Analog modules
9.2 SM 336; AI 6 x 13 Bit
189