Siemens SIMATIC S7-300 Reference Manual page 198

Digital Modules
Terminal assignment and block diagram of the SM 323; DI 8/DO 8 x 24 VDC/0.5 A
Figure 3-38 Module View and Block Diagram of Digital Input/Output Module SM 323;
DI 8/DO 8 x 24 VDC/0.5 A
3-114
M
Backplane bus
interface
Channel number
Status display – green
1M
2L+
2M
Programmable Logic Controllers S7-300 Module Data
24V
24V
A5E00105505-03