Honeywell Digital Output, Relays ( 8 channel) 900TBR-0001
Modem requirementsMost commercially available modems can be used with the HC900 Controller. The modem must have the
following capabilities:
RS-232 interface
Auto answer
Can operate at 1200, 2400, 4800, 9600, 19200, 38400, 57600 baud; recommended 9600 or 19200 or
38400 baud, 8 data bits, 1 stop bit, and no parity
Hardware handshaking can be disabled
Software handshaking can be disabled
Data Terminal Ready (DTR) input can be disabled
Result codes can be suppressed
Echo can be disabled
Must be equipped with non-volatile memory (NVRAM) so that settings that are configured using
command strings can be retained during a power-outage
Must be able to load the NVRAM settings automatically on power-up
Cable requirements
You will need an interface cable to connect the modem to the 25-pin connector, be sure to use a DB-25 to
DB-9 modem cable. TIP
The Null Modem cable used to directly connect a PC running Designer Software to
the controller may typically not be used to connect the PC to the modem or to
connect the modem to the controller.
If your modem requires command string configuration, you will need an interface cable to connect the
modem to your PC. Refer to your modem and computer documentation to determine this cable’s
requirements.

Modem configuration
Before connecting a modem to the controller’s RS-232 port (marked “CONFIGURATION”), the modem
must be configured with the following settings:
Baud Rate = 1200, 2400, 4800, 9600, 19200, 38400, 57600 (Must match Baud Rate configured in
HC900 Controller)
Parity = None
1 stop bit
8 data bits
No handshaking
Ignore DTR
Suppress result codes
Suppress echo
Auto answer
Disable command recognition (only necessary if the modem has this capability)
Some of these settings may be settable via switches. Others may require command strings to be written to
the modem using a PC terminal program such as Hyperterminal. You will need to refer to your modem’s
documentation to make this determination. Those settings that are configured using command strings must
be saved to the modem’s non-volatile RAM (NVRAM), and the NVRAM must be configured as the profile
that gets loaded when the modem is powered up.
Most modems are equipped with auto-recognition to set the baud rate, parity, stop bits, and data bits. If
your modem has no means of setting these using switches, then most likely it is equipped with autorecognition. To configure the port settings of a modem with auto recognition, do the following:
Step Action
1 Connect the modem to a PC.
2 Power up the modem.
3 Start up a PC terminal program such as Hyperterminal.
4 Configure the PC COM Port for 1200, 2400, 4800, 9600*, 19200*, 38400*, 57600 baud (must
match Baud Rate configured in HC900 Controller), no parity, 1 stop bit, and 8 data bits.
*recommended
5 Establish communications with the modem. A common way of doing this is simply entering the
AT E1 Q0 command and seeing if the modem responds with OK.
Once you establish communication to the modem, its port settings are configured.
6 Save the port settings to the profile that gets loaded on power-up.
Modem configuration examples
Below are procedures for setting up the following commercially available modems:
3Com US Robotics 56K Data/Fax External Modem
Zoom 56K Dualmode External Modem (page 142)
Best Data 56SX Data Fax External Modem (page 143)
SixNet VT-MODEM Industrial External Modem (page 144)
3Com US Robotics 56K Data/Fax External Modem
Step Action
1 Ensure that the switches are set to the factory settings:
Switch Setting Position Function
1 OFF UP Normal DTR operations
2 OFF UP Verbal (word) results
3 ON DOWN Enable result codes
4 OFF UP Displays keyboard commands
5 ON DOWN Disables auto answer
6 OFF UP Modem sends CD signal when it connects with another modem
7 OFF UP Loads Y0-Y4 configuration from user-defined
nonvolatile memory (NVRAM)
8 ON DOWN Enables recognition (smart mode)
2 Connect the modem to a PC. If your computer’s RS-232 port has a 25-pin connector, use a
DB-25 male to DB-25 female RS-232 cable. If your computer’s RS-232 port has a 9-pin
connector, use a DB-25 male to DB-9 female modem cable.
3 Power-up the modem.
4 Run a serial communication port program such as Hyperterminal.
5 Within the communication program, select the port to which the modem is connected.
6 Configure the port to these settings:
baud rate = 1200, 2400, 4800, 9600, 19200, 38400, 57600 (Must match Baud Rate
configured in HC900 Controller)
data bits = 8
parity = none
stop bits = 1
flow control = none
7 In the program's terminal window, restore factory defaults by keying-in the following command
string:
AT &F0
Then, press the ENTER key.
The modem should respond with OK.