User manual
IEC61131 User and Reference Manual 
April 22, 2008     
608 
Modem Commands 
The dial and inimodem functions and the ISaGRAF program dial-up connection operate with 
Hayes AT command set compatible external modems. The commands specify how the 
modem behaves. Each modem manufacturer has a different set of modem commands 
required to initialize the modem. 
This appendix lists modem initialization command strings for a number of modems. If your 
modem is not on the list try the generic modem settings.  
Modem Settings 
If generic modem settings do not work, fill out the table below by looking up the commands 
in your modem manual. Construct a command string from the results. Your modem may not 
require all the commands or may require additional commands. Please contact our 
Technical Support department if you require assistance. 
Command 
Description 
reset modem to factory or default settings 
(This command should be sent first.) 
select extended result code set 
return verbal responses 
do not echo characters in command state 
return actual state of carrier detect (CD) signal 
hang up when DTR signal is dropped 
disable (local) flow control 
Communicate at a constant speed between DTE and modem 
answer incoming calls on the first ring 
carrier wait time = 50 seconds 
Note that command strings do not begin with AT. The AT will be inserted automatically when 
the commands are sent to the modem. 
Generic Modem 
This command string works with many Hayes compatible modems. 
String 
X4 V1 E0 &C1 &D2 S0=1 S7=50 
Command 
Description 
X4 
select extended result code set 
V1 
return verbal responses 
E0 
do not echo characters in command state 
&C1 
return actual state of carrier detect (CD) signal 
&D2 
hang up when DTR signal is dropped 
S0=1 
answer incoming calls on the first ring 
S7=50 
carrier wait time = 50 seconds 










