Remark 2: Failsafe function of CS31 bus

Further information on the failsafe function of the CS31 bus are contained in the chapter “The failsafe function of S500 I/O devices”.

Further S500 modules can be coupled to the base module “DC551-CS31” via the I/O bus. Right-clicking the element “DC551-CS31” in the configuration tree and selecting the menu item “Append Subelement” displays all available input/output modules that can be added to the module “DC551-CS31”.

A maximum of 7 expansions with a total of 240 DI / 240 DO and 40AI / 40 AO can be appended to the module.

The following peculiarities concerning the CS31 bus in the AC500 must be observed when addressing S500 I/O devices at the CS31 bus:

1. A CS31 software module can occupy a maximum of

   • 15 bytes of inputs and 15 bytes of outputs in the digital area.

     This corresponds to 15 x 8 = 120 digital inputs and 120 outputs.

2. A CS31 software module can allocate a maximum of

   • 8 words of inputs and 8 words of outputs in the analog area.

3. A maximum of 31 of these CS31 software modules are allowed for connection to the CS31 bus.

4. If a device has more than 15 bytes or 8 words of inputs or outputs, it occupies 2 or more of the 31 CS31 software modules.

5. The DC551-CS31 can internally manage 2 CS31 software modules in the digital area and 5 CS31 software modules in the analog area. This corresponds to a maximum of:

   • 240 digital inputs (2 x 15 bytes) and
   • 240 digital outputs (2 x 15 bytes) and
   • 40 analog inputs (5 x 8 words) and
   • 40 analog outputs (5 x 8 words).

6. Address setting is done at the DC551-CS31 using two rotary switches at the module’s front plate.

7. To enable the fast counter of the DC551-CS31, the hardware address (HW_ADR) has to be set to the module address + 70. With activated fast counter, the module addresses 0..28 (hardware address setting 70..98) are allowed.

   Then, the DC551-CS31 registers as 2 CS31 software modules using the module address (hardware address 70), once in the digital area and once in the analog area.

8. • CS31 software module 1 in digital area:

     -> registers using the module address.

     • -> registers using module address+7 and bit “Channel >= 7” set.

       CS31 software module 1 in analog area:

     • CS31 software module 2 in digital area:

       -> registers using the module address.

     • CS31 software module 2 in analog area:

       -> registers using module address and bit “Channel >= 7” set.

     • CS31 software module 3 in analog area:

       -> registers using the module address+1.

     • CS31 software module 4 in analog area:

       -> registers using module address+1 and bit “Channel >= 7” set.

9. The DC551-CS31 can manage a maximum of 255 parameters.

   This does not cause any restrictions in all configurations with the currently available S500 I/O devices.

10. The next free address for a DC551-CS31 is derived from the highest address occupied in the digital area or the analog area of the previous DC551-CS31.

11. When connecting several S500 expansion modules to a DC551-CS31 via the I/O bus, their inputs and outputs follow the DC551-CS31’s inputs and outputs without gap. Such a cluster can occupy up to 6 CS31 software modules.

12. A maximum of 7 S500 expansion modules (extensions) can be connected to a DC551-CS31.

A configuration consisting of two combined input/output modules could look as follows:

Note

The fast counters of the input/output modules (e.g., “DC532”) are only available if the modules are connected to the CPU’s I/O bus.