USING PPP OVER A MODEM
SNAP PAC R-Series Controller User’s Guide
12
Configuring PPP on the Controller
To configure PPP on the SNAP PAC R-series controller, see instructions in the
(form 1704)
.
Also use this guide to assign an IP address to the Ethernet ports, configure points, and store
configuration to flash.
Attaching the Modem to a SNAP PAC R-Series Controller
Once the controller and I/O points are configured and communication has been tested, follow these steps to
attach the modem to the controller. To work properly with the controller, a modem must be able to store
settings in non-volatile RAM (NVRAM) and default to those settings on reset.
IMPORTANT: Any modem used with the controller must implement the Carrier Detect (CD) signal or use a custom
cable that connects CD to Data Terminal Ready (DTR) on the controller side.
1.
Use the following diagram to attach the modem to the controller using the serial connector. As shown
here, you can use either a DB9 or a DB25 connection.
NOTE: Pins 3 and 6 are tied together within the SNAP PAC R-series controller, so no external jumper is required.
2.
Store configuration settings to the modem’s NVRAM, following instructions in the user’s guide for your
modem.
NOTE: Configuration settings must be stored to the modem’s NVRAM so they will be loaded when the SNAP PAC
R-series controller sends a reset command to the modem.
3.
If PCs will dial up the controller, set up Windows dial-up networking on the PCs that will call the
controller.
Modem
DB25
TD
2
RD
3
RTS
4
CTS
5
SG
7
CD
8
DTR
20
Controller
1
TX
2
RX
4
RTS
5
CTS
3 or 6
COM
8
DCD
7
DTR
Modem
DB9
DCD
1
RX
2
TX
3
DTR
4
RTS
7
CTS
8
SG
5
Controller
8
DCD
2
RX
1
TX
7
DTR
4
RTS
5
CTS
3 or 6
COM
