D.10
SEL-787 Relay Instruction Manual Date Code 20150130
DNP3 Communications
DNP3 in the SEL-787
synchronization messages.) It can be set to request time synchronization
periodically by setting the TIMERQn setting to the desired period. It can also
be set to not request, but accept time synchronization (TIMERQn = M for
“master”).
Modem Support
The SEL-787 DNP implementation includes modem support for serial ports.
Your DNP3 master can dial-in to the SEL-787 and establish a DNP3
connection. The SEL-787 can automatically dial out and deliver unsolicited
DNP3 event data.
When the device dials out, it waits for the “CONNECT” message from the
local modem and for assertion of the device CTS line before continuing the
DNP transaction. This requires a connection from the modem DCD to the
device CTS line.
NOTE: Contact SEL for information
on serial cable configurations and
requirements for connecting your
SEL-787 to other devices.
You can either connect the modem to a computer and configure it before
connecting it to the SEL-787, or program the appropriate modem setup string
in the modem startup string setting MSTR. You should use the PH_NUM1
and (optional) PH_NUM2 settings to set the phone numbers that you want the
SEL-787 to call. The SEL-787 will automatically send the ATDT modem dial
command and then the contents of the PH_NUM1 setting when dialing the
modem. If PH_NUM2 is set, the RETRY1 setting is used to configure the
number of times the SEL-787 tries to dial PH_NUM1 before dialing
PH_NUM2. Similarly, the RETRY2 setting is the number of attempts the
SEL-787 tries to dial PH_NUM2 before trying PH_NUM1. MDTIME sets the
length of time from initiating the call to declaring it failed because of no
connection, and MDRET sets the time between dial-out attempts.
NOTE: RTS/CTS hardware flow
control is not available for a DNP3
modem connection. You must use
either X-ON/X-OFF software flow
control or set the port data speed
slower than the effective data rate of
the modem.
The settings PH_NUM1 and PH_NUM2 must conform to the AT modem
command set dialing string standard, including:
➤ A comma (,) inserts a four second pause
➤ If necessary, use a 9 to reach an outside line
➤ Include a 1 and the area code if the number requires long
distance access
➤ Add any special codes your telephone service provider
designates to block call waiting and other telephone line
features.
DNP3 Settings
The DNP3 port configuration settings available on the SEL-787 are shown in
Table D.7. You can enable DNP3 on Ethernet Port 1 or on any of the serial
Ports 2 through 4, to a maximum of three concurrent DNP3 sessions. Each
session defines the characteristics of the connected DNP3 Master, to which
you assign one of the three available custom maps.
Because some settings apply only to serial DNP3, they are visible only when
configuring a serial port. Likewise, settings that apply only to DNP3 LAN/
WAN are visible only during Ethernet port configuration.
For example, you only have the ability to define multiple sessions on Port 1,
the Ethernet port. The IP address for each session must be unique. Setting the
IP address to 0.0.0.0 allows any master IP address to connect to the session, as
long as that IP address is not configured for another DNP3 session. Only one
connection is supported on the session at a time.
Extreme care should be observed to ensure network security, especially when
setting the IP address to 0.0.0.0, as there is no limitation on the DNP3 master
that may connect to the session.
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