E.13
Date Code 20090730 Instruction Manual SEL-734 Meter
Distributed Network Protocol
EIA-232 Physical Layer Operation
EIA-232 Physical Layer Operation
The RTS signal may be used to control an external transceiver. The CTS
signal is used as a DCD input, indicating when the medium is in use.
Transmissions are only initiated if DCD is deasserted. When DCD drops, the
next pending outgoing message may be sent once an idle time is satisfied. This
idle time is randomly selected between the minimum and maximum allowed
idle times (i.e., MINDLY and MAXDLY).
In addition, the SEL-734 monitors received data and treats receipt of data as a
DCD indication. This allows RTS to be looped back to CTS in cases where the
external transceiver does not support DCD. When the SEL-734 transmits a
DNP message, it delays transmitting after asserting RTS by at least the time in
the PREDLY setting. After transmitting the last byte of the message, the
SEL-734 delays for at least PSTDLY milliseconds before deasserting RTS.
If the PSTDLY time delay is in progress (RTS still high) following a
transmission, and another transmission is initiated, the SEL-734 transmits the
message without completing the PSTDLY delay and without any preceding
PREDLY delay. The RTS/CTS handshaking may be completely disabled by
setting PREDLY to OFF. In this case, RTS is forced high and CTS is ignored,
with only received characters acting as a DCD indication. The timing is the
same as above, but PREDLY functions as if it were set to 0, and RTS is not
actually deasserted after the PSTDLY time delay expires.
LDP Select Date/Time
40,41 40 Seconds
40,41 41 Minutes
40,41 42 Hours
40,41 43 Day
40,41 44 Month
40,41 45 Year
VSSI Select Date/Time
40,41 46 Milliseconds
40,41 47 Minutes
40,41 48 Hours
40,41 49 Day
40,41 50 Month
40,41 51 Year
Miscellaneous
50 N/A Time and Date
60 N/A Class Data
80 N/A Internal Indications
112 N/A Virtual Terminal Output Block
113 N/A Virtual Terminal Event Data
Table E.5 DNP3 Device Profile (Sheet 9 of 9)
DNP Object
Type
Index Description Scaling and Deadband
Courtesy of NationalSwitchgear.com
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