1.3
SIM Interface
1 – 5
Direction
Pin
Signal
Src
⇒
Dest
Description
1
SIGNAL GND
MF
⇒
SIM
Ground reference for signal
2
−
STATUS
SIM
⇒
MF
Status
/
service request (GND
=
asserted,
+
5 V
=
idle)
3
RTS
MF
⇒
SIM
HW handshake (
+
5 V
=
talk; GND
=
stop)
4
CTS
SIM
⇒
MF
HW handshake (
+
5 V
=
talk; GND
=
stop)
5
−
REF 10MHZ
MF
⇒
SIM
10 MHz reference (no connection in SIM980)
6
−
5 V
MF
⇒
SIM
Power supply (no connection in SIM980)
7
−
15 V
MF
⇒
SIM
Power supply
8
PS RTN
MF
⇒
SIM
Power supply return
9
CHASSIS GND
Chassis ground
10
TXD
MF
⇒
SIM
Async data (start bit
=
“0”
= +
5 V; “1”
=
GND)
11
RXD
SIM
⇒
MF
Async data (start bit
=
“0”
= +
5 V; “1”
=
GND)
12
+
REF 10MHz
MF
⇒
SIM
10 MHz reference (no connection in SIM980)
13
+
5 V
MF
⇒
SIM
Power supply
14
+
15 V
MF
⇒
SIM
Power supply
15
+
24 V
MF
⇒
SIM
Power supply (no connection in SIM980)
Table 1.1: SIM Interface Connector Pin Assignments, DB-15
1.3.2.1
Direct interface cabling
If the user intends to directly wire the SIM980 independent of the
SIM900 Mainframe, communication is usually possible by directly
connecting the appropriate interface lines from the SIM980 DB–15
plug to the RS-232 serial port of a personal computer.
1
Connect RXD
from the SIM980 directly to RD on the PC, TXD directly to TD, and
similarly RTS
→
RTS and CTS
→
CTS. In other words, a null-modem
style cable is
not
needed.
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 SIM980, 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.
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. The serial baud rate is
fixed, but the word size and parity may be changed with the
FLOW
or
PARI
commands.
1
Although the serial interface lines on the DB-15 do not satisfy the minimum
voltage levels of the RS-232 standard, they are typically compatible with desktop
personal computers
SIM980
Analog Summing Amplifier