page
1
phone: 360.260.2468
l
sales: 800.736.0194
l
fax: 360.260.2469
email: sales@usdigital.com
l
website: www.usdigital.com
11100 ne 34th circle
l
vancouver, washington 98682 USA
AD2-A
SEI to RS232 Adapter
US
Digital
C o r p o r a t i o n
TM
Ordering Information:
Technical Data, Rev. 04.02.03, April 2003
All information subject to change without notice.
Price:
$48 / 1
$45 / 10
$40 / 50
$37 / 100
$34 / 500
$31 / 1K
Cost Modifiers:
Subtract $5 for NP-option (no power supply).
Includes:
PS-9V (power supply).
The AD2-A adapter allows the RS485-like signal of SEI devices to interface to a standard
RS232 port (25-pin DSUB), such as those in IBM compatible PCs. The SEI (Serial Encoder
Interface) bus is a simple, quick and convenient network of SEI devices interfacing to
a RS232 serial port. The SEI bus supports from 1 to 15 devices on a single 6-wire
telephone-type cable, up to 1000 feet long. For more information on the SEI bus please
see the SEI data sheet.
The AD2-A has 2 differential signals to interface to SEI devices: the bidirectional data
pair for communication, and the busy input pair for data flow control. The wall-mount
power supply connected to the AD2-A furnishes power for all SEI devices on the bus.
Attention: Our 9-pin DB adapter is now available and recommended for newer
computers. For more information see our AD2-B data sheet.
US Digital warrants its products against defects in materials and workmanship for two
years. See complete warranty for details.
Description:
AD2-A -
NP = No power supply.
Parameter
Min.
Max.
Units
Storage temperature
-40
100
C
Operating temperature
0
70
C
Humidity (non-condensing)
0
95
%
120 VAC input power
-
6
Watts
Absolute Maximum Ratings:
Specifications apply over entire operating temperature range.
Typical values are specified at Vcc=12V and 25C.
Electrical Characteristics:
Parameter
Min.
Typ.
Max.
Units
Input voltage (into PS-9V)
100
-
130
VAC
Supply voltage (into AD2-A)
8.0
-
16
Volts
Supply current (without encoders)
-
-
15
mA
Differential output voltage*
2.0
-
10
Volts
|DataL - DataH|, |Busy+ - Busy-|
Differential input voltage
0.2
-
14
Volts
|DataL - DataH|, |Busy+ - Busy-|
Common mode output voltage*
-
2.5
3.0
Volts
(DataH+DataL)/2, (Busy-+Busy+)/2
* Load = 100 Ohms.
Electrical Characteristics:
Parameter
Min.
Typ.
Max.
Units
Common mode input voltage
-7.0
-
12
Volts
(DataH+DataL)/2, (Busy-+Busy+)/2
Input current (In = 0 to 5V)
-15
-
15
mA
DataH, DataL, Busy-, Busy+
RS232 output high (RXD, BUSY)
5.0
8.0
-
Volts
RS232 output low (RXD, BUSY)
-
-8.0
-5.0
Volts
RS232 input high (TXD, DRIVE)
3.5
-
15
Volts
RS232 input low (TXD, DRIVE)
-15
-
0.4
Volts
Mechanical Drawing:
Example SEI Network:
PS-9V
AD2-A
Adapter
USD-SW
Software
To Computer
AD5 Quadrature Encoder to SEI
Adapter
A2 Absolute Encoders
ED2 Digital Readout
TM
US Digital's
SEI Bus
page
2
phone: 360.260.2468
l
sales: 800.736.0194
l
fax: 360.260.2469
email: sales@usdigital.com
l
website: www.usdigital.com
11100 ne 34th circle
l
vancouver, washington 98682 USA
AD2-A
SEI to RS232 Adapter
US
Digital
C o r p o r a t i o n
TM
MOD-6
Name
Description
DSUB
Name
Description
1
GND
Ground, common for power, data and busy pairs.
2
TXD
Data input from host, normally low
2
Busy+
Differential input line, active high, has 330 Ohm pull down
3
RXD
Data output to host, normally low
3
Busy-
Differential input line, active low, has 330 Ohm pull up
5
RTS
Not connected
4
PWR
Power supply output to encoder bus
4
BUSY
Busy line to host, active low (CTS)
5
DataL
Bidirectional differential data line, has 330 Ohm pull up
7
GND
Ground, common for RS232 signals
6
DataH
Bidirectional differential data line, has 330 Ohm pull down
Functional Pin Description:
1) The lines busy+ and busy- are differential, but they should not be terminated. They are biased in the AD2 adapter with pull-up/down resistors to keep them
in the inactive state (busy+ with 330 Ohm to ground, busy- with 330 ohm to +5V) when they are not driven.
2) The lines dataL and dataH are RS485 differential lines; they do not need to be terminated for cables 1000 ft long at 19.2 kbaud (proportionally shorter at
higher baud rates, i.e. 200 ft at 115 kbaud). They are biased in the adapter with pull-up/down resistors to keep them in the idle state (dataL with 330 Ohm
to +5V, dataH with 330 Ohm to ground) when the bus is not driven. If terminated, make sure the lines are biased such that dataL is at least 2 volts above
dataH.
3) The analog version of the A2 absolute encoder can be connected to this adapter, but the BUSY signal cannot be used for handshaking. Since the AD2
adapter loads these lines, the full analog voltage range will not be reached when connected to the AD2. If simultaneous serial communication and analog
output is needed, the analog output line pair should be broken and intercepted before reaching the AD2.
4) The power supply requirement of the AD2 is 5.5 Volts min. This should be considered carefully when long cables are used, because of the voltage drop
caused by the cable's resistance (a typical 26AWG telephone-type cable is 40 Ohms per 1000 feet). For example, the AD2 provides 8 volts worst case,
which can support 2 encoders at 1000 feet of cable, or 4 encoders at 500 feet, etc.
5) The AD2-A has 2 differential signals to interface to the encoders: the bidirectional data pair for communication and the busy input pair for data flow control.
The RS485 data transmitter of the AD2 is automatically enabled whenever the RS232 transmit line (TXD) goes high and for about 10 usec after it goes low.
The busy input pair is connected to the BUSY (RS232 CTS) input of the host PC.
6) The power supply input is used for the internal circuitry and is connected to the SEI bus PWR line for the encoders.
Notes:
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