Encom ENC-900, Operating Manual

ENC-900 Operating Manual: Chapter 3 Configuration Options

17

DATA

MODE

POWER-UP

SEQUENCE

COMMAND

MODE

USER TYPES 'mhx'

5 sec elapses

or

characters

other than

 'mhx'

entered by 

the user

(A

TA

 o

r A

TO

 C

om

m

an

d)

D

TR

 o

r 

Es

ca

pe

 S

eq

ue

nc

e

Figure 5A.  S0=1, S119=1 

(factory default) 

DATA

MODE

POWER-UP

SEQUENCE

COMMAND

MODE

500 msec

(A

TA

 o

r A

TO

 C

om

m

an

d)

D

TR

 o

r 

Es

ca

pe

 S

eq

ue

nc

e

Figure 5B.  S0=1, S119=0  

DATA

MODE

POWER-UP

SEQUENCE

COMMAND

MODE

500 msec

(A

TA

 o

r A

TO

 C

om

m

an

d)

D

TR

 o

r 

Es

ca

pe

 S

eq

ue

nc

e

Figure 5C.  S0=0 

The escape sequence will not 
be accepted unless both the 
ENC-900 and the terminal 
are set to the same baud rate

The terminal must be set for 9600 baud 8N1 in order for the modem to 
accept these characters.  If ‘enc’ is typed incorrectly, the modem will 
immediately enter into data mode.  If the five seconds elapses without any 
response from the user, the modem will go into data mode. 

In command mode, the module “autobauds,” meaning that it will adapt to the 
baud rate of the DTE equipment to which it is connected.  Therefore, when in 
command mode, you may change the baud rate of your equipment, and the 
ENC-900 will automatically adjust to this baud rate once an AT string is 
issued.  The new baud rate is stored in register S102.  Several baud rates 
ranging from 1200 to 115200 may be selected.   

You can place the modem into Data Mode from Command Mode either by: 

•

Issuing the answer command (ATA <ENTER>); or, 

•

Issuing the online command (ATO <ENTER>). 

With traditional telephone line modems, these two commands serve different 
purposes, however, with the ENC-900, these commands are identical.   The 
modem will now attempt to communicate with other ENC-900 modules.  
While in Data Mode, the modem will communicate through the serial port at 
the same baud rate as was last used in Command Mode

2

. 

To return to Command Mode, you can either: 

•

Send the escape sequence.  (The escape sequence consists of 1 
second of inactivity, followed by the characters ‘+++’ followed by 
another second of inactivity.); or, 

•

Toggle the DTR line (depending on the &D parameter). 

The escape sequence must be issued at the baud rate that the modem has 
been set to.  If the modem is set to 19200 baud, and the escape sequence is 
issued at 9600 baud, for example, the modem will not recognize it, and will 
not go into Command Mode. 

Figure 5 provides a state diagram for power-up, command mode, and data 
mode.  Note that there are three different variants of the state diagram which 
depend on the values of registers S0 and S119.  See the appropriate sections 
for more details about these registers.  The factory defaults are S0=1 and 
S119=1.

2

 It is possible to enter into Data Mode at a different baud rate from what is 

currently being used in Command Mode by issuing the command 
ATS102=x, where x is one of the valid baud rates.  Care must be taken when 
setting the baud rate in this manner.  If you issue another AT string after 
attempting to set the baud rate using ATS102 <ENTER>, the modem will 
again autobaud and automatically revert to the baud rate of the host 
equipment.  For example, if your equipment is running at 9600 baud and you 
wish to set up the modem to run at 19200 baud, the following command line 
entry would be suitable:     
 

ATS102=5&WA <ENTER> 

The first part (S102=5) sets the baud rate to 19200.  The next characters 
(&W) write this baud rate to memory.  The last character (A) puts the 
modem into Data Mode.  Once in Data Mode, the modem is unable to 
autobaud, and is fixed at 19200 baud.  By combining several commands into 
one command line entry, and then immediately putting the modem online, 
the modem is not given a chance to autobaud back to 9600.