Communications wiring
WSHP Open v3
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Integration Guide
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9
Adjusting BACnet MS/TP properties using an Equipment Touch
You may need to adjust the following BACnet MS/TP protocol timing settings using the Equipment Touch.
Max Masters
- defines the highest MS/TP Master MAC address on the MS/TP network.
For example, if there are 3 master nodes on an MS/TP network, and their MAC addresses are 1, 8, and 16, then
Max Masters would be set to 16 (since this is the highest MS/TP MAC address on the network).
This property optimizes MS/TP network communications by preventin
g token passes and “poll for master”
requests to non-existent Master nodes.
In the above example, MAC address 16 knows to pass the token back to MAC address 1, instead of counting up to
MAC address 127. Each MS/TP master node on the network must have their Max Masters set to this same value.
The default is 127.
Max Info Frames
- defines the maximum number of responses that will be sent when the WSHP Open receives the
token. The default is 10 and should be ideal for the majority of applications. In cases where the WSHP Open is the
target of many requests, this number could be increased as high as 100 or 200.
NOTES
•
BACnet MS/TP networks can be comprised of both master and slave nodes. Valid MAC addresses for master
nodes are 0
–
127 and valid addresses for Slave nodes are 0 - 254.
•
If the third party attempts to communicate to the controller but does not get a response, make sure the
controller is set as a BACnet MS/TP (m) master. The BACnet s
oftware asks the controllers, “Who Is?” This is
to auto-locate devices on the network. Only controllers set as masters will answer this request.
•
See Appendix A for Network Points List.
•
See
Appendix B
(page 45) for the BACnet Protocol Implementation Conformance Statement (PICS).
To set the Device Instance number or adjust the Max Masters or Max Info Frames using an Equipment Touch
1
In the Equipment Touch interface, navigate to the
Properties Menu
screen and click
Login
.
NOTE
The following graphic is generic and not specific to your system.
