Siemens SIMATIC TI500 Especificações descarregar pdf (Página 310)

Enhancements in Late Model CPUs

F-5

SIMATIC 545/555/575 System Manual

NOTE: Be careful not to enter duplicate I/O references, because the first

reference found is the one that is used.

Due to the previously mentioned special code that is generated by the CPU’s

compiler, the configuration of a DP slave that has an associated immediate

instruction can no longer be changed while a PLC is in run mode. If

attempted, the error message “ILLEGAL REQUEST IN CURRENT

OPERATIONAL MODE” will be given. You must make changes to the

DP-configuration in Program mode so that the required program-to-run

transition occurs to cause an RLL compile.

Immediate instructions can be added or deleted at any time to any correctly

configured points using the run-time edit function.

In order to estimate a typical fast DP I/O update time for your application,

the following time components should be considered:

1. Buffer access: a DP buffer is accessed in less than 0.1 ms (unless

consistency is selected).

2. DP data-cycle-time: an estimate of DP data-cycle-time is given by the

COM PROFIBUS software tool.

3. DP-RBC (Remote Base Controller) data-cycle-time: a SIMATIC 505

DP-RBC reads/writes discrete modules every 2 ms and word/analog

modules every 4 ms. This delay is not present for modules that connect

directly to PROFIBUS-DP.

4. Module delay time: module delay time is given in the SIMATIC 505

Input/Output Modules User Manual for each SIMATIC 505 module.

Delay times for other slaves can usually be obtained from their

documentation.

Given a 12 Mbaud network with a 53-slave configuration, COM PROFIBUS

estimates a typical data-cycle-time of 2.7 ms for the PROFIBUS-DP

channel. For a SIMATIC 505 discrete AC module in the local base, an IORW

(immediate) requires 10.5 ms to complete. Shifting the module to a DP base

increases its update time to 17.5 ms. The difference, 7 ms, is within the

calculated typical update bounds of 4.7 ms (2.7 + 2.0) to 9.4 ms ( 5.4 + 4.0) of

the DP and 505 DP-RBC update cycles.

This is a worst-case scenario. Normally, faster DC I/O modules are used in

applications where response speed is important, and stand-alone slaves do

not have delays such as those created by the RBC. Therefore, use the

considerations described above in order to select proper components and

settings for your project.

Changing a

PROFIBUS-DP Slave

Configuration

Typical Update

Time

Example

1 2 ... 305 306 307 308 309 310 311 312 313 314 315 ... 321 322

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