This article is part of a guided learning series on building our understanding of the Siemens S7-1200 PLC.
Canonical Article: Navigating Siemens S7-1200 PLC model numbers
Learning Companion (Q&A): Learning Companion Navigating Siemens S7-1200 PLC model numbers
You are reading: Question 6
What is the difference between a standard S7-1200 and the new S7-1200 second generation (G2) PLC?
Comparison based on specifications
The S7-1200 G2 is an incremental improvement over the original S7-1200. The specifications are similar as seen in this comparison between the CPU 1212C and CPU 1212C G2. We see that the G2 has more memory and reduced power subsumption. This implies that the underlying microcontroller and supporting hardware has been upgraded. Consider the specifications for the CPU 1212C and CPU 1212C G2.
Specification for the SIMATIC S7-1200, CPU 1212C 6ES7212-1HE40-0XB0
- Compact CPU, DC/DC/relay
- Onboard I/O: 8x DI 24 V DC, 6 DO relay 2 A, 2 AI 0-10 V DC,
- Power consumption: 9 W
- Memory:
- Work memory integrated: 100 kB
- Load memory integrated: 2 Mb
Specification for the SIMATIC S7-1200, CPU 1212C 6ES7212-1HG50-0XB0
- Compact CPU 1212C DC/DC/RLY
- Power supply: DC 20.4-28.8 V DC
- Onboard I/O: 8x DI 24 V DC with 6 DO relay 2 A
- Power consumption: 3 W
- Memory:
- Work memory integrated: 650 kB
- Load memory integrated: 8 Mb
Comparison based on physical size
The G2 CPU has a slight size advantage when compared to the original. For instance, the featured CPU 1212C is 90 mm while the CPU 1212C G2 is 70 mm. This size reduction is an important consideration for panel construction and could potentially be the determining factor in moving to a lower sized (less costly) panel.
Size advantage based on the G2’s improved modularity
The Siemens G2 PLCs feature advanced signal boards (plug-in modules) that enable further size reductions. An example is shown in Figure 1 where a type SB 1223 plug in module. This relatively low-cost module provides an additional four digital inputs plus four high speed digital outputs. Note that this picture is taken from the Siemens TIA configuration tool.
Cost advantage of the S7-1200 G2 PLC
The Siemens signal boards install directly into the G2 PLC. Consequently, they have less embodied physical materials and cost less than corresponding G2 expansion modules such as the SM 1223 expansion module.
The signal board plus the smaller PLC is a double advantage provided your PLC needs can be met with G2 and signal board.
Figure 1: Image of the S7-1212C G2 with a SB 1223 module providing 4 additional inputs and 4 high-speed digital (transistor) outputs.
Article by Aaron Dahlen, LCDR USCG (Ret.), Application Engineer at DigiKey