Allen-Bradley Rockwell Automation 857 User Manual page 216

7-10
Communications
Communication Protocols
(cont.)
857-UM001A-EN-P – July 2009
The following ASDU (Application Service Data Unit) types will be
used in communication from the device:
•
ASDU 1: time tagged message
•
ASDU 3: Measurands I
•
ASDU 5: Identification message
•
ASDU 6: Time synchronization and
•
ASDU 8: Termination of general interrogation.
The device will accept:
•
ASDU 6: Time synchronization
•
ASDU 7: Initiation of general interrogation and
•
ASDU 20: General command.
The data in a message frame is identified by:
•
type identification
•
function type and
•
information number
These are fixed for data items in the compatible range of the
protocol, for example, the trip of I> function is identified by: type
identification = 1, function type = 160 and information number = 90.
"Private range" function types are used for such data items, which
are not defined by the standard (e.g. the status of the digital inputs
and the control of the objects).
The function type and information number used in private range
messages is configurable. This enables flexible interfacing to
different master systems.
Table 7.8 – Parameters
Parameter Value
Addr 1 – 254
bit/s
9600
19200
MeasInt 200 – 10000
SyncRe
Sync
Sync+Proc
Msg
Msg+Proc
Set = An editable parameter (password needed)
Unit Description
An unique address within the system
bps Communication speed
ms Minimum measurement response
interval
ASDU6 response time mode
Note
Set
Set
Set
Set