From 8287bbcb15cb62b22d3784ae7032d6dfb3b7d99b Mon Sep 17 00:00:00 2001 From: David Koenigs Date: Mon, 23 Oct 2023 08:23:09 +0200 Subject: [PATCH] Description readmee --- README.md | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/README.md b/README.md index 4bc4ff6..1fb8054 100644 --- a/README.md +++ b/README.md @@ -1,6 +1,33 @@ # @simatic-ax.lacyccom ## Description +The following section shows a scenario for a possible application of the LAcycCom +library: + +With acyclic data exchange, contrary to cyclic communication, data transfer takes +place when an explicit request is made, e.g. in order to read and write drive object +parameters. Acyclic parameter access occurs parallel to the cyclic process data +exchange. This saves resources, since the data is only requested on demand, i. e. +when a parameter has to be transferred. +The "Read data record" and "Write data record" services are available for acyclic +data exchange. +According to the PROFIdrive profile, for drives in conformance with PROFIdrive, +only one DPV1 (asynchronous PROFIBUS communication) request is permissible +for each drive object and control unit for non-cyclic (acyclic) communication +(parameter requests). If two or more DPV1 requests are simultaneously issued to a +drive unit, conflicts can occur when processing the request in the drive unit. These +conflicts then cause the different DPV1 requests to mutually interfere with one +another. In order to prevent that such bus conflict occurs, it is the user’s +responsibility to avoid that and a check must be made for each new DPV1 request +whether another request is already active on the drive object involved. This is +certainly the case if system functions are also used that are not exclusively +intended to communicate to drive units via DPV1 services. +In order to relieve the user of this task a request management called Resource +Manager exists that handles the management of DPV1 services for the user. This +function is presented here. However, the introduction of this request management +assumes as prerequisite that each function, which utilizes DPV1 services, will also +actually use them. + ## Install this package