Pacific Research Solutions RI-1 - Manual (Page 14)

Pacific Research Solutions RI-1 and PE-1 User Manual
Page 8
MODEM INTERFACE
You should be able to use about any external modem that operates at 9600 baud or higher, can auto answer and operate in a
dumb terminal mode. In this application, we used a US Robotics external modem to connect to the controller. On the back of
the USR modem, you will find a configuration dipswitch. Set all of the dipswitches in the up position, except for switch 4,
which will be down. When using other modems, consider the following settings:
• Data Terminal Ready (DTR) - normal
• Suppress result code
• No echo, off line commands (Echo Off)
• Auto answer on first ring or higher, depending on shared telephone line
• Carrier detect - normal
• Dumb terminal mode, disable command recognition
For people who want to share the telephone line between the modem and the controller, we have three different methods
available:
1. Ring Delay: With this method, you connect the telephone line to the modem and then connect the phone jack output from
the modem to the controller. Set up the modem to answer on 2 more rings then the controller. Example: set the controller
to answer after 2 rings and set the modem to answer after 4 rings. Then create a user command that sets S-Command 71 to
mode 0, disabling incoming calls. When you want to establish a connection with the controller’s modem, execute the user
command and then call the modem the controller will not answer the call. Once you are finished or during the modem
connection, reset the incoming call mode to 2 or higher. Now, the controller will answer calls before the modem answers.
2. Call switch box: This method uses a modem/voice switch box. This is a box that into which the telephone line plugs.
The box modem port is connected to the modem and the box voice telephone port is connected to the controller. When a
call comes in, the box will direct the call to the modem or controller.
3. Power control: With this method, you connect the telephone line to the modem and then connect the phone jack output to
the controller. Connect a relay so that it will switch the power supply line of the modem. Use one of the controller’s
digital outputs to control the relay. Create two user commands to turn the relay on and off. Set the modem to answer on
the first ring and the controller to answer on 2 or more rings. When you want to call the modem, execute the user
command to power the modem and then call the modem. Once you are finished, send the user command to power down
the modem. Now the controller will answer the calls and the modem will not.
Vertex Programming Cable to Modem Cable
If you are using the PL-3 ProgramLink, you can use a standard modem cable to connect your modem to the PL-3. If you are
using the Vertex programming cable, you need to build a modem-to-modem cable because the Vertex cable works in the same
manner as a modem. The following schematic shows how to build a modem-to-modem cable for a modem equipped with DB-
25 connector or DB-09 connector.