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iEM3100 / iEM3200 / iEM3300 series user manual Communications via BACnet
DOCA0005EN-04 89
Chapter 8 Communications via BACnet
What is in this chapter?
This chapter contains the following sections:
BACnet communications overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
BACnet protocol support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
BACnet communications implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
BACnet object and property information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
BACnet communications overview
Communications via BACnet MS/TP protocol is available on the iEM3165, iEM3265 and iEM3365.
The information in this section is intended for users with an advanced understanding of BACnet
protocol, their communications network and their power system.
Key terms
Related topics
• See www.bacnet.org for more information on the BACnet protocol.
BACnet protocol support
Go to www.schneider-electric.com and search for your meter model to access the PICS (Protocol
Implementation Conformance Statement) for your meter.
The meter supports the BACnet protocol as follows:
Term Definition
APDU Application protocol data unit, that data portion of a BACnet message.
Confirmed message A message for which the device expects an answer.
COV
Change of value, sets the amount by which a value has to change in order for the meter to send a
subscription notification.
Device
A BACnet device is a unit that is designed to understand and use BACnet protocol (for example, a
BACnet-enabled meter or software program). It contains information about the device and device
data in objects and object properties. Your meter is a BACnet device.
MS/TP Master-slave/token-passing over RS-485.
Object
Represents the device and device data. Each object has a type (for example, analog input or binary
input) and has a number of properties.
Present value The current value of an object.
Property
The smallest piece of information in BACnet communications, it consists of a name, data type and
value.
Service Messages from one BACnet device to another.
Subscription
Creates a relationship between the server and the meter, so that when the present value property
of an object changes by more than the configured COV threshold (COV_Increment), a notification is
sent.
Subscription notification The message the meter sends to indicate a COV event has occurred.
Unconfirmed message A message for which the device does not expect an answer.
BACnet component Description
Protocol version 1
Protocol revision 6
Standardized device profile (Annex L) BACnet Application Specific Controller (B-ASC)