IDP-782 - Hardware Guide
3.5.3 RS-232
The RS-232 interface defaults to the following settings: 9600 bit/s, 1 start, 8 data, 1 stop bit, and no parity.
The baud rate is configurable up to 115,200 bps.
The electrical characteristics of the interface are:
Parameter
Min.
Typical
Max.
Units
Rx Input Low Threshold for DTE Connected
-
-
-2.7
V
Rx Input High Threshold for DTE Connected
2.7
-
-
V
Rx Threshold for DTE Disconnected
-0.3
-
0.3
V
Serial Rx Input Low Threshold
0.6
-
-
V
Serial Rx Input High Threshold
-
-
2.4
V
Rx Input Voltage Range
-25
-
25
V
Serial Tx Low Output (3 kΩ load)
-
-
-3.7
V
Serial Tx High Output (3 kΩ load)
3.7
-
-
V
ESD Protection
Human Body Model
-
±15
-
kV
Contact Discharge Model
-
±8
-
kV
3.5.4 iButton Reader
The iButton 1-Wire interface allows connection to downstream 1-Wire devices connected on a bus, or to a
single button reader. Relative to any attached iButton device the terminal behaves as the master. The
iButton driver supports 3 or 5 V devices on the bus.
At standard speed, the iButton supports up to 39 devices over a 60 meter CAT5 cable. In overdrive, the
usable expected distance is reduced to ≤ 15 meters with a maximum node count of 9.
The electrical characteristics of the interface are:
Parameter
Min.
Typical
Max.
Units
Input High Voltage
1.8
-
-
V
Input Low Voltage
-
-
0.6
V
Output Low Voltage
-
-
0.2
V
Load Current @ 3 V
-
4
-
mA
ESD Protection
Human Body Model
-
±27
-
kV
T213, Version 02
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