IEC 61131-5:2000 pdf download

IEC 61131-5:2000 pdf download.Programmable controllers -Part 5:communications.
6.2.1 Device verIfication
This function is provided to allow other devices to determine if the PC is able to perform its intended function in the automated system. A PC can provide status of itself and its subsystems. Status includes health and state information. A device may explicitly request status from the PC or the PC may initiate an unsolicited status report using services provided by the communication interface. See 6.1 for the d.fnition of health and state information of a PC system and of its subsystems.
Table 10 — D.vic. v•rlflc.tlon f.atur.s
6.2.2 Data acquisition
Data contained in a PC is presented as variables. This data may come from a variety of sources and may have a wide range of meanings. It can be obtained by the client through one of several methods.
a) Poll•d — The client reads the value of one or more varlabl•s at a time or condition determined by th. client. The access to the variables may be controlled by the PC. Only selected variables are accessible over the network.
b) Programmed — The data is provided by the PC to the client at a time or condition determined by the PC application program.
C) Configured — The communications interface to the PC can be configured by a client to initlat• a data transfer to the client.
The kinds of variables in the PC which are visibl• to the communication system are:
a) variables with direct representation;
b) oth•r variables which have access paths (see IEC 61131-3 (or the definition of access paths).
If the directly represented vanablea are accessible for communication these variables shall use the direct representation as an identifier, The PC server (i.e. the PC which owns the variables) can interpret th. identifier using an implementer defined algorithm.
The PC system may restrict access to variables with direct representation. The conditions (size, location. etc.) under which each data type supported by th• PC can be uninterruptedly accessed shall be specilbed by the implementer.
82.6 Application program execution and LIO control
Execution of a PC Application Program Is managed by the Apphcation Program Execution function se. 5.2). PC Application Programs can be started and stopped. PC Application Programs can be started either from an initial state or from the stat. they were in at the tim. they were stopped
The PC application program In a PC system consists of one configuration and zero, one or more resources (see lEG 61131.3). Configurations and resources may be started and stopped. The resources ar• started and stopped when the configuration is started and stopped and they can be started or stopped independently of the configuration.
The Interlace Function to Actuators (outputs) associated with a running Application Program can b directed to •ith•r use the values supplied by the Application Program or held In a known stale. This Interface state is specified at th• time the Application Program state is changed. The outputs can be directed to either be set to implementer specified states, hold the outputs in the current state, set all outputs to zero, or change some outputs to user specified states (on or oil. with those not specified holding the last state) through an impl.ni.nter specified mechanism (for example, tables. PC procedure, .tc.).
The Interlace Function to Sensors (inputs) associated with a running Application Program can be directed to either provide the actual data from th. sensors or to contlrio. to use previously supplied valu•s. The input state is specified at the time the Application Program state is changed.
The I/O (inputs and outputs) associated with a running resource shall either be controlled by the program or held in a known stati, which is determined when the resource is started. Resources shall be able to be started either from an InitIal state (cold restart using START) or from the State they were In at the time they were stopped (warm restart using RESUME). The desired state of the outputs shall be able to be specified as part of the stopping process.
The state of the 110 can be set to the following values when a configuration or resource is
started or stopped.