Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 74)

Publication AG-UM008C-EN-P - February 2005
3-6 Configuring MicroLogix 1100/1200/1500 Controllers
Using Modems that Support
DF1 Communication
Protocols The types of modems that you can use with MicroLogix
1100/1200/1500 controllers include dial-up phone modems,
leased-line modems, radio modems and line drivers. For
point-to-point full-duplex modem connections, use DF1 full-duplex
protocol. For general point-to-multipoint modem connections, use
DF1 half-duplex master and slave protocols. In this case, one (and
only one) of the other devices must be configured for DF1 half-duplex
master protocol. For most radio modem connections, use DF1 radio
modem protocol.
Dial-up Phone Modems
Dial-up phone line modems support point-to-point full-duplex
communications. Normally, a MicroLogix 1100/1200/1500 controller
on the initiating or receiving end of the dial-up connection, will be
configured for DF1 full-duplex protocol with the control line
parameter set for no handshaking.
When a MicroLogix 1100/1200/1500 controller is the initiator of the
dial-up connection, use one of the ASCII write instructions to send out
the AT dial-up string (for example ATDT 555-1212). For the
MicroLogix 1500 LRP channel 1 only, bit (CS1:9/3) provides the
feedback that the connection has been successfully made. To hang up
the connection, return the modem to Command Mode and use an
ASCII Write instruction to send out the ATH hang-up string.
See Chapter 11 for further details on using MicroLogix 1100/1200/1500
controllers in dial-up modem applications.
IMPORTANT
Do not attempt to use DH-485 protocol through
modems under any circumstance.