C-more Protocol Timing Settings

 Topic: CM472

General Rules of How The Panel Formulates Requests

The C-more Panel optimizes its Data Request as much as the Protocol will allow. This means that it will take the Object addresses on the screen and any addresses being updated in the background (i.e., Event Manager Tags, PLC to Panel Tags, Trend Graphs, etc.) and put them together in as few Requests as possible.

The screen configuration shown below will necessitate three separate requests from the panel. Some general rules of why the panel must separate the requests are:

  • Different Data types require different requests.
  • Long gaps between addresses within a Data type (generally about 128 bytes is the rule).
  • In addition, the Panel separates requests from Dynamic Text Objects because of their varying length.

Poll Time and Timeout

When setting up PLC Protocols to work with the C-more Panels, there are two Timing fields that may be available during the set-up process. A sample of these fields is shown below followed by a description for each.

  1. Timeout: This represents the time allowed for a response. The Response Time is the time that the Panel measures between sending out a request and receiving a response. If this time exceeds the Timeout setting entered in the Timeout field, then the Panel will display a PLC Timeout Error on the screen.
  2. Poll Time: This represents the time that the Panel “injects” between when it receives the last response and before it sends the next request.

The figure below is a diagram showing how the requests and responses reflect the Response Time and how after the Poll Time is completed, a second request is sent. The process repeats constantly.

Reasons for Adjusting Poll Time

  • To get faster updates on the Panel, reduce the Poll Time as much as possible.
  • If the device the Panel is communicating with has a heavy load (i.e., long scan times, other devices communicating with it, etc.), increase the Poll Time to allow other processes to get serviced better.
  • Example: Multiple C-more Panels to one PLC using ECOM. The ECOM is bottlenecked by the backplane. The ECOM can only send one request to the CPU via the backplane per scan. So if the PLC scan is long and multiple C-more Panels are requesting data, the ECOM buffer can overload. Increase the Poll Time to help with this situation.

Reasons for Adjusting Timeout

  • If the PLC scan is long, you may have to increase the Timeout value to compensate. Our PLC will only respond with Data once per scan.
  • Using Radio Modems or other converters that create a delay in the response.
  • If you get PLC Timeout Errors on the panel and all of the rest of the settings have been verified, this is the setting to try to adjust next.