1
3
A
B
C
4–3
Operation (Computer) – 4
The modem attached to the unit must have the
following AT command configuration:
E0
No Echo
Q1
Don’t return result code
&D3
On to OFF DTR, hang-up and reset
&S0
DSR always on
&C1
DCD ON when detected
S0=2
Answer on second ring
The following commands may also be required at
the modem:
&Q6
Constant DTE to DCE
N0
Answer only at specified speed
W
Disable serial data rate adjust
\Q3
Bi-directional RTS/CTS relay
&B1
Fixed serial port rate
S37
Desired line connection speed
There are some variation in the AT commands
supported by manufacturers of Hayes-compatible
modems. Refer to the hardware user documentation
for a list of supported AT commands and direction
on issuing these commands.
Setting Up the M-3520 Intertie Protection Relay
for Communication
The initial setup of the relay for communication
must be completed by the optional M-3931 HMI
Module or using direct serial connection using the
default “As Shipped” communication parameters.
Refer to Communication Data and Unit Setup “AS
SHIPPED” form located in Appendix A,
Forms
.
For units shipped without the optional HMI Module,
the communication parameters may be altered by
first establishing communication using the default
parameters and the IPSutil™ program.
IPSutil is an auxiliary program shipped on the same
disk with the IPScom program. It is used exclusively
for altering communication and setup parameters
on units shipped without the M-3931 HMI Module.
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■
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■
NOTE:
Communication is inhibited while the
relay is in local mode (being accessed
using the HMI). To ensure the M-3520 is
available for remote communication,
press
ENTER
at the
EXIT LOCAL MODE
menu item, or press the
EXIT
key several
times to back out of the menu tree to the
top level screen.
1.
Connecting the modem to the computer:
a. If the computer has an external
modem, use a standard
straight-through RS-232 modem
cable to connect the computer and
modem (M-3933). If the computer
has an internal modem, refer to the
modem’s instruction book to
determine which communications
port should be selected.
b. The Hayes-compatible modem must
be attached to (if external) or
assigned to (if internal) the same
serial port as assigned in IPScom
®
.
While IPScom can use any of the
four serial ports (COM1 through
COM4), most computers support
only COM1 and COM2.
c. Connect the modem to the telephone
line and power up.
2.
Connecting the Modem to the Relay:
Setup of the modem attached to the
relay may be slightly complicated. It
involves programming the parameters
(using the AT command set), and storing
this profile in the modem’s nonvolatile
memory.
After programming, the modem will power
up in the proper state for communicating
with M-3520. Programming may be
accomplished by using “Hyperterminal”
or other terminal software. Refer to your
modem manual for further information.
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■
NOTE:
The relay does not issue or understand
any modem commands. It will not adjust
the baud rate and should be considered
a “dumb” peripheral. It communicates
with 1 start, 8 data, and 1 stop bit.
a. Connect the unit to an external
Hayes-compatible modem by
attaching a standard RS-232 modem
cable to the appropriate serial
communications port on both the
unit and the modem.
b. Connect the modem to the telephone
line and power up.
Summary of Contents for M-3520
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