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7/12/2010 5:43 PM | |
Posts: 5 Rating: (1) |
When you have multiple devices under a single channel the server talks to those device synchronously, or one device at a time. The total poll cycle is the amount of time it takes to get all of the data from all the devices. For example if it took 100msec to get the data from each indicifgual devcice and you had 7 devices then it would take a minimum of 700msec for all of the devices once. If a device is not active then the server must timeout on it. the default timeout for a device is 1000msec with 3 attempts. This means it will take a total of 3000msec for the server to fail that device and move to the next device. If you multiple devices failing then you have added quite a bit of time to the poll cycle. The solutions: 1. We recomend placeing each device on its on channel. Most drivers in the server support at least 100 channel. The server treats each channel as a seperate communicaitons thread and will process them simultaneously. If a device is unavaialbe it will not impact the communications with the rest of the devices. You can contact Kepwere Technical Support(technical.support@kepware.com) for information on how to convert a singel channel project to a multi channel project with out having to change your client project. 2. Most drivers support device auto demaotion. this allows you to configure the device in the server so that it is demoted from the poll cycle after a certain number of consecutive communications failures. You then define how long the server will wait to see if the device is availalbe again for communicaiotns. 3. You can change the request timeout and attempts so that a request fails faster and tries fewer time. Fred Loveless Kepware Tehcnologies. |
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