Issue
Communications between a DMS-3500 and a Niagara R2 UNC-520 is slow. Points are updating very slowly. What are some settings that can be verified and/or optimized?
Environment
Niagara R2 UNC-5x0
DMS-35, DMS-350A, DMS-3500
Cause
There could be several variables: high count of polled objects, lower than optimal baud rate between the UNC and the DMS, non-optimal settings for the DMS Comm Service, etc....
Resolution
Review the Best Practices section of the DMS Serial Driver Engineering Guide (F-27071) and apply as many of the suggestions as possible. Among them, here are the suggestions that do not require a hardware modification or an architectural change:
- Use the maximum allowable baud rate for the DMS serial port (38.4kb for a DMS-3500)
- Adjust the property settings of the DmsCommService to match the following:
- intermessageDelay = 1500
- timeoutHostMsg = 215000
- timeoutHostFragment = 110000
- maxReadValues = 10
- downDeviceRecoveryInterval = 1
- maxMultipleMsgs = 3
- autoCycleTimeOn = TRUE
- deltaCycleDifference = 10
- deltaCycleChange = 25
- globalCycleTime = 15000
- Ensure any DMS point alarms, that are no longer required, are programmed to not annunciate to the serial port being used to interface to the UNC.
- Optimize polling by customizing the minimumPollInterval setting for each shadow object. The default setting is 1000 ms. A space temperature sensor, for example, changes very slowly. Its setting can be modified to be anywhere from 30000 ms to 60000 ms.
- Keep the number of Poll-Always points below 600 if they are polling at 1000 ms.
