6ES5921-3UA11 - CPU - SIEMENS

The S5-135U / 155U programmable controller is part of the SIMATIC S5 family of programmable controllers. This device can be used in single-processor and multi-processor architecture, with a maximum of four CPUs. In a multiprocessor configuration, each CPU processes its own user program, independently of the other CPUs.

The S5-135U / 155U programmable logic controllers consist of a base frame (ZG) and - if necessary - one or more expansion frames (EG). Expansion chassis are used when the number of slots available in the base chassis is not enough to accommodate all the necessary cards.

For the ZG - EG and EG - EG coupling, there are different couplers (IM). It is thus possible to install the EGs in the immediate vicinity of the ZG (centralized expansion configuration) or to deport them at a greater or lesser distance (decentralized expansion configuration). A mix of these two types of assembly is also possible since EG can be connected in a centralized configuration to a decentralized EG

The S5-135U / 155U base chassis can accommodate the following CPUs:
- CPU 948,
- CPU 928B,
- CPU 928,
- CPU 922.
A programmable controller in which a CPU 948 is mounted is an S5-155U. A PLC configured with a CPU 928B, 928, or 922 (but without a CPU 948) is an S5-135U.

In the CPU 948, 928B-3UB21 and 928-3UA21, you can use a flash EPROM memory card on which your user program is stored. In the case of CPU 928B, 928 and 922, this storage is carried out by means of memory cartridges (RAM or EPROM).

The CPU 948 and 928B have a second serial interface in addition to the PG interface. An interface module is required to allow physical adaptation.