I.2
SEL-311C Relay Instruction Manual Date Code 20060320
DNP Communications
Configuration
Configuration
To configure a port for DNP, set the port PROTO setting to DNP. Although
DNP may be selected on any of the available ports, DNP may not be enabled
on more than one port at a time. The information provided in Tabl e I.1 is
required to configure a port for DNP 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., MAXDLY and MINDLY). In addition, the SEL-311C
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-311C 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-311C 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-311C 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
Table I.1 Data Needed to Configure a Port for DNP
Label Description Default
SPEED Baud rate (300–38400)
a
a
38400 is not available on Port 1.
2400
DNPADR DNP Address (0–65534) 0
ECLASS Class for event data (0–3) 2
TIMERQ Time-set request interval (0–32767 min.) 0
DECPLA Currents scaling (0–3 decimal places) 1
DECPLV Voltages scaling (0–3 decimal places) 1
DECPLM Miscellaneous data scaling (0–3 decimal places) 1
STIMEO Select/operate time-out (0–30 sec.) 1.0
DRETRY Data link retries (0–15) 3
DTIMEO Data link time-out (0–5 sec.) 1
MINDLY Minimum time from DCD to Tx (0–1 sec.) 0.05
MAXDLY Maximum time from DCD to Tx (0–1 sec.) 0.10
PREDLY Settle time from RTS on to Tx (OFF, 0–30 sec.) 0
PSTDLY Settle time after Tx to RTS off (0–30 sec.) 0
ANADB Analog reporting dead band (0–32767 counts) 100
UNSOL Enable Unsolicited reporting (Y, N) N
PUNSOL Enable Unsolicited reporting at power up (Y, N) N
REPADR DNP Address to report to (0–65534) 0
NUMEVE Number of events to transmit on (1–200) 10
AGEEVE Age of oldest event to transmit on (0–60 sec.) 2.0
UTIMEO Unsolicited confirmation timeout (0–50 sec.) 2
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