Product Name:  Siemens S7-1500 PLC Digital,Input,Module SM522

Brand Name: Siemens 

6ES7521-1FH00-0AA0

This function enables an I/O module to be shared by up to four IO controllers. At present the IM 155-5 PN ST supports two IO controllers. An IM that permits a distribution to up to four IO controllers is in preparation. This feature enables the use of I/O modules with many channels, that are the distributed over several IO controllers. The latter can all be located in the same station. In the case of digital modules the assignment is on the basis of load groups, with analog modules it is on a channel basis. The logic assignment is to a so-called "Submodule". It is also possible to assign all these Submodules to a single IO controller. In this case the I/O addresses of the modules are not assigned on a block basis, but each Submodule can be assigned its own address.

Example:

o If a 32-DI module is normally assigned to one IO controller, it occupies e.g the addresses EB8, EB9, EB10 and EB11 in one block. Only the basic address (EB8) can be changed; the other addresses cannot be changed.

o However, if the module is configured as submodule-granular Shared Device, these four Bytes can be freely assigned with addresses, e.g. EB8, EB18, EB20 and EB30.

User benefits of submodule-granular Shared Device

Reduced costs due to saving of modules and IO-Devices

Less space required in the switchboard due to saving of modules and IO-Devices

Free address assignment for flexible program creation

Module-internal Shared Input (MSI)

The function Module-internal Shared Input (MSI) enables an input module to share its input data with up to four IO controllers. Each controller can make a read access to the same channels. When these modules are used together with the interface module IM 155-5 PN DP (6ES7 155-5 AA00-0AB0), up to two controllers are supported. In the case of a MSI configuration of an input module the input values of all channels are copied to a Basis Submodule (=main controller) and up to three additional MSI Submodules. The channels of the module are then available with identical input values in the Basis Submodule and the MSI Submodules. Each IO controller can make reading access to the same channels.