Honeywell HC900 User And Installation Manual page 152

Modem requirements
Most 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.
138 HC900 Process & Safety Controller User and Installation Manual Revision 6
21 April 2017