Heath Consultants Heath Data Recorder (HDR) - Manual (Page 9)

9
External Modem
The HDR is equipped with two RS232 communication ports. The Direct Port is dedicated to local direct PC
communication at 19200 baud using the HDR com cable. The Remote Port is used for connecting a modem. Remote
baud rates available are 300, 1200, 2400 (default), 4800, 9600 and 19200. When configuring for a remote modem, the
“Remote Modem Baud Rate” in the unit must match the baud rate of the field modem being used. Connect the RX, TX &
GND from the modem to the instrument on J13. A wiring harness is required for this connection.
Note: For proper remote communication using the native protocol Sandia, the modem [default] mode needs to remain.
Modbus mode must be set to “RTU” & “Parity” must be set to “None”.
Note: If the external modem powers down to save power, the CTS wire is required to wake the modem prior to “dialing out upon
alarm”- if this feature is enabled. Otherwise the CTS wire isn’t required for inbound communication.
Caution: When connecting the HDR to an external modem, it is recommended to connect external power to the
instrument due to higher current demand.
CT
S
RT
S
CD T
XM
RXM GND
GND
INDEX B
STOBE
INDEX A
STOBE
3V SYS
GND
GAS TEMP 2
1.5VDC
GND
12VDC
GND
BUTTON
JP5
CR2032
3V
1 2 3
ASSY#: 77R65-9320
REV F
3.6V "AA" Lithium
OPEN
JP1
DISPLAY
BACKUP BATTERY
WIRED TO
Modem Wakeup
Jumper Wire
CTS
GND
RX
TX
(Only required for modems that power down)
(Only required for modems that power down)
J13
Non-Heath Modem
D
SR
(Pi
n
6)
G
N
D
(P
in
5)
R
X (Pi
n 2)
TX (Pin
3)
RS-232
Splice
Splice
Splice
Splice
9 Pin
12V
GND
12VDC Modem
Battery
12V GN
D
+ -
External power is recommended
When connected to external modems.