About Tuning The Max Info Frames Parameter; About Tuning The Max Master Parameter; Setting The Max Master And Max Info Frames - Acuity Controls nLight ECLYPSE User Manual

Hide thumbs Also See for nLight ECLYPSE:

Table of Contents

BACnet MS/TP Communication Data Bus Fundamentals

ECLYPSE

Figure 100: Setting the Max Master on the ECLYPSE Controller to the Highest MAC Address Used on the BACnet MS/TP Data Bus

About Tuning the Max Info Frames Parameter

Once a device has the token, it can make a number of information requests to other devices on the BACnet intranetwork.

The maximum number of requests is limited by the Max Info Frames parameter. Once the device has made the maximum

number of requests it is permitted to make according to the Max Info Frames parameter, the device passes the token to

the following device with the next higher MAC address. This makes the BACnet MS/TP Data Bus more reactive for all de-

vices by preventing a device from hanging on to the token for too long. Ordinary BACnet MS/TP devices should have the

Max Info Frames parameter set to between 2 and 4. The Data Bus Master (ECLYPSE Controller) should have the Max

Info Frames parameter set to 20.

To prevent the passing of the token to unused MAC Addresses situated after the final Master device, the Max Master pa-

rameter must be set. By default, the Max Master for an ECLYPSE Controller or a Supervisor is set to 127 which allows for

the theoretical maximum of 127 devices besides the Data Bus Master to be connected to the data bus.

In practice, the actual number of devices connected to a data bus is far less, resulting in a gap between the highest MAC

Address of any device connected to the data bus and the value set for Max Master. This gap unnecessarily slows down

the data bus with Poll for Master requests.

When commissioning a BACnet MS/TP Data Bus, it is useful to start with the Max Master set to 127 so as to be able to

discover all devices connected to the data bus. Then, once all devices have been discovered and the MAC Addressing is

finalized by eliminating any gaps in the address range, set the Max Master (maximum MAC Address) in the ECLYPSE

Controller and in the Supervisor to the highest Master device's MAC Address number to optimize the efficiency of the data

bus.

The Max Master and Max Info Frames are parameters used to optimize a BACnet MS/TP Data Bus. This is set in the

ECLYPSE Controller and separately with the Supervisor for each connected BACnet MS/TP device.

nLight ECLYPSE

102

Table of Contents

Show Quick Links

Table of Contents

Do you have a question about the nLight ECLYPSE and is the answer not in the manual?