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--- controls:protocols:bacnet:qna [2020/10/02 03:54] – old revision restored (2020/09/20 21:08) 92.220.10.100
+++ controls:protocols:bacnet:qna [2020/10/04 00:48] – old revision restored (2020/09/30 16:24) 92.220.10.100
@@ Line 1: / Line 1: @@
-====== Questions / Answers ======
+====== Questions and Answers ======
 Here are a few interesting Q&A gathered from the BACnet mailing list.
-==== max_info_frames ====
+===== Broadcasts =====
+??? Can devices ignore Who-Is broadcasts?
+When sending a Who-Is broadcast, I have some devices that won't answer I-Am like I would expect them to.
-=== Question ===
+- Christian Fortin
-<code>
+!!!
-Does anyone have experience as to adjusting the max_info_frames to increase overall network speed?
+(…) broadcasts can and will get lost, especially when there are a lot of them. If you broadcast a Who-Is with no parameters, ALL devices have to answer, so you will get a flurry of I-Am, some of which may get dropped.
-Would it matter if the devices do NOT support read_property_multiple?
-- Bob Kline
+- John Hartman
-</code>
-=== Answer ===
+!!! See the related [[http://blog.hvac.io/2015/01/11/network-discovery-with-devices-ignoring-whois/|blog post]]
-<code>
+??? Should a BACnet/IP router answer to global broadcast messages?
+New version of the Tridium Jace bacnet module, if configured to act as a bacnet/ip - MSTP router, will respond to "local" broadcast message (ex. 192.168.1.255)
+But not to Global broadcast messages (ex. 255.255.255.255)
+- Christian Tremblay
+!!!
+B/IP messages sent to 255.255.255.255 should be handled as normal BACnet broadcasts, as that address is reserved for broadcasting on the local subnet. So, these messages should be handled identically to messages sent to the broadcast address of the subnet.
+- Coleman
+===== max_info_frames =====
+??? Can adjusting the max_info_frames increase overall network speed?
+Would it matter if the devices do NOT support read_property_multiple?
+- Bob Kline
+!!!
 Adjusting max_info_frames can improve performance – or make it worse.
@@ Line 28: / Line 47: @@
 - John Hartman
-</code>