1 – 8
Getting Started
To interface directly to the DB–9 male (DTE) RS-232 port typically
found on contemporary personal computers, a cable must be made
with a female DB–15 socket to mate with the SIM928, and a female
DB–9 socket to mate with the PC’s serial port. Separate leads from
the DB–15 need to go to the power supply, making what is sometimes
know as a “hydra” cable. The pin-connections are given in Table 1.2.
DB–15
/
F to SIM928
Name
DB–9
/
F
3
←→
7
RTS
4
←→
8
CTS
10
←→
3
TxD
11
←→
2
RxD
5
Computer Ground
to P
/
S
7
←→
−
15 VDC
13
←→
+
5 VDC
15
←→
+
24 VDC
8,9
←→
Ground (P
/
S return current)
1
←→
Signal Ground (separate wire to Ground)
Table 1.2: SIM928 Direct Interface Cable Pin Assignments
1.3.2.2
Serial settings
The initial serial port settings at power-on are: 9600 Baud, 8–bits, no
parity, 1 stop bit, and RTS
/
CTS flow control. These may be changed
with the
BAUD
,
FLOW
, or
PARI
commands.
The maximum
standard
baud rate that the SIM928 supports is 38400.
The minimum baud rate is 110. Above 38400, the SIM928 can be
set to the following (non-RS-232-standard) baud rates: 62500, 78125,
104167, 156250. Note that these rates are typically not accessible on
a standard PC RS-232 port, but can be used between the SIM928 and
the SIM900 Mainframe.
SIM928
Isolated Voltage Source
