Manual revision 001
Section 2: Description of SBE 39
plus
-IM
SBE 39
plus
-IM
16
Inductive Modem Module (IMM) or Surface Inductive Modem (SIM)
An Inductive Modem Module or Surface Inductive Modem is required for
communication with the SBE 39
plus
-IM. These devices impress (
modulate
)
the mooring cable with a DPSK signal that is encoded with commands
received from the computer/controller. The encoded signals are
demodulated
by 39
plus
-IMs coupled to the cable. Replies from 39
plus
-IMs are similarly
coupled to the cable and
demodulated
by these devices.
The SBE 39
plus
-IM requires a minimum of 20 ohms impedance.
Inductive Modem Module (IMM)
The IMM must be supplied with 7 to 24 volts DC power. The maximum
operating current is approximately 15 milliAmps.
The user’s computer or buoy controller is interfaced via RS-232 serial port to
the IMM. The standard interface protocol between the computer/controller and
IMM is 1200, 2400, 4800, 9600, 19200, or 38400 baud (user-selectable);
8 data bits; no parity; RS-232C.
The DPSK communication link between the IMM and IM instrument(s) is
half-duplex, so talking and listening is sequential only. Although the data link
between the IMM and the user’s computer/controller is established at 1200,
2400, 4800, 9600, 19200, or 38400, the DPSK modem communication
between IMM and IM instruments always operates at 1200 baud.
See the IMM Manual for details.
Surface Inductive Modem (SIM)
The SIM must be supplied with 7 to 25 volts DC power. The maximum
operating current is approximately 30 milliAmps.
The user’s computer or buoy controller is interfaced via RS-232 serial port to
the SIM. The standard interface protocol between the computer/controller and
SIM is 1200, 2400, 4800, or 9600 baud (user-selectable); 8 data bits; no parity;
RS-232C; with echoing of characters.
The DPSK communication link between the SIM and IM instrument(s) is half-
duplex, so talking and listening is sequential only. Although the data link
between the SIM and the user’s computer/controller is established at 1200,
2400, 4800, or 9600 baud, the DPSK modem communication between SIM
and IM instruments always operates at 1200 baud.
Note:
The 39
plus
-IM includes an
integrated
IMM in its housing. This section is
referring to the IMM or SIM that is
connected to the controller. These are
referred to as
remote
to differentiate
from the integrated IMM.
