|
Q: |
|
How do the converters
derive power? Do I need to turn ON DTR or RTS in order to power the
converters? |
|
|
Q: |
|
How do I know my converters
are powered and functioning well? |
|
|
Q: |
|
The converters are
port-powered. Why is there a +5V sign on the converters? Can I connect
external power to this terminal? |
|
|
Q: |
|
Can I plug / unplug the
converters while they are being used? |
|
|
Q: |
|
What is DTE / DCE? How do I
know my RS-232 Device is a DTE or a DCE? |
|
|
Q: |
|
What are Handshake Lines? |
|
|
Q: |
|
Do I need to use handshake
lines to control the data direction? |
|
|
Q: |
|
My control software
requires handshake lines to be tied together (e.g. DTR & DCR, RTS &
CTS). Can I still use your converters? |
|
|
Q: |
|
What are the supported Baud
Rates? |
|
|
Q: |
|
Do I need to set the baud rate
on the converters for them to work with different serial devices? |
|
|
Q: |
|
Can I use converters to
extend the RS-232 data line distance? |
|
|
Q: |
|
What is SMT? What are the
benefits of using a SMT Circuit Card? |
|
|
Q: |
|
What is the current
consumption of your converters? |
|
|
Q: |
|
What is the maximum
distance the converters can communicate with remote
devices? |
|
|
Q: |
|
How many serial devices
can I connect with the port-powered converters? |
|
|
Q: |
|
When do I need to turn ON the terminator
(120Ω
End of Line Resistor)? |
|
|
Q: |
|
What type of cable is
recommended for RS-485/RS-422 connections? |
|
|
Q: |
|
What is GND? Can I connect
it to the Earth? |
|
|
Q: |
|
What is a Static
Protection Circuit? Is it a Surge Suppressor? |
|
|
Q: |
|
What is Opto-isolation?
What are the benefits of using Opto-isolated converters? |
|
Q: |
|
What are the differences
of using Surge Suppressors and Opto-Isolators?
|
|
Q: |
|
Will the converters work
with new computers? |
|
|
Q: |
|
Will the converters work
with USB to RS-232 Cables/Converters? |
|
|
Q: |
|
Can I use your converters
without using the terminal block provided? |
|
|
Q: |
|
How do I use CVT-485_422-1/CVT-485_422-3
as a RS-232/RS-422 converter? |
|
|
Q: |
|
How do I perform a
Loopback Test for my RS-232/RS-485 converter? |
|
|
Q: |
|
How do I perform a
Loopback Test for my RS-232/RS-422 converter? |
|
Q: |
|
How do I perform a
Loopback Test for my RS-232/TTL converter? |
|
Q: |
|
How do I perform a
Loopback Test for my RS-232 COM port? |
|
Q: |
|
Can I use more than one
RPT-485_422-2 to extend the RS-485/422 distance? |
|
Q: |
|
What is the maximum number
of supported nodes in a RS-485/RS-422 circuit if the RPT-485_422-2
is used? |
|
|
Q: |
|
What should I know about
the Product Warranty? |
|
|
|
|
Q: |
|
How do the converters derive power?
Do I need to turn ON DTR or RTS in order to power the converters? |
|
| |
|
The converters are powered by RS-232
Data Line (Pin 3 of DTE devices - DB9 Connector), unlike most of the port-powered
converters available in the market (which steal power from handshake
lines), our converters do NOT require any handshake signal (e.g. DTR
or RTS). This is very useful as most of the RS232 devices do NOT have
their handshake lines turned ON, and that's the reason why our
converters can be used for almost ALL RS-232 devices. |
|
| |
|
|
|
|
Q: |
|
How do I know my converters are
powered and functioning well? |
|
| |
|
There is a +5V pin on the termination board attached to the
converter. Measure this pin and the Gnd. If you
get more than +5V, your converters are powered correctly. Otherwise,
please check your connection. For example, if the converter is
connected to a DCE device, you need to swap Pin 2 and 3 (or use a
Null-modem converter to connect in between the device and the
converter).
You can also use CommFront's
232Analyzer
software (An Advanced Serial Port - RS232 /RS485 /RS422
/TTL
Analyzer) to perform a Loopback Test.
Click
here
to download a FREE copy of 232Analyzer software. |
|
| |
|
|
|
|
Q: |
|
The converters are port-powered. Why
is there a +5V sign on the converters? Can I connect external power to
this terminal? |
|
| |
|
The +5V sign on the termination board is
used for measurement only. Do NOT connect any external power to this
pin. If you doubt that the converter is not functioning, measure this pin
and the Gnd with a Volt meter. If you get a signal of more than +5V, your
converters are powered correctly, otherwise please check your
connection. For example, if the device the converter is connected to is a DCE
device, you need to swap Pin 2 and 3 (or use a
Null-modem converter to connect between the device and the
converter). |
|
| |
|
|
|
|
Q: |
|
Can I plug / unplug the converters
while they are being used? |
|
| |
|
Yes, the converters come with a Data
Transceiver Protection Circuit (to protect the Data Transceiver inside
the converter) and therefore are hot-pluggable. |
|
| |
|
|
|
|
Q: |
|
What is DTE / DCE? How do I know my
RS-232 Device is a DTE or a DCE? |
|
| |
|
DTE
stands for Data Terminal Equipment, a PC is a DTE. DCE stands for Data
Communication Equipment, a Modem is a DCE.
DTE normally comes with a Male Connector, while DCE comes with a
Female Connector, but that is not always the case. Use the guide below
as a simple way to confirm: |
|
|
|
>> Measure Pin 3 and Pin 5 (DB9
Connector) with a Volt Meter. If you get a voltage of -3V to
-15V, it is a DTE device. If the voltage is on Pin 2, then it is
a DCE device. Note: The result for the DB-25 Connector is reversed, and Ground
for the DB-25 is on Pin 7.
|
|
|
|
To learn more about
RS-232, check out:
RS-232 Tutorial - the basics: Three easy steps to understand and control
your RS232 devices |
|
|
|
|
|
|
Q: |
|
What are Handshake Lines? |
|
| |
|
Handshake Lines are used to control the
direction of data flow between DTE and DCE. They are: |
|
|
|
RTS (Request to Send) - Asserted by DTE to prepare DCE to receive
data. |
|
|
|
CTS (Clear to Send) - RTS Acknowledgment by DCE to allow DTE to
transmit. |
|
|
|
DTR (Data Terminal Ready) - Asserted by DTE to indicate that it is
ready to be connected. |
|
|
|
DSR (Data Set Ready) - Indicates an
active connection by DCE. |
|
|
|
DCD (Data Carrier Ready) - Used by modem
when a connection has been established with remote equipment. |
|
|
|
RI (Ring Indicator) - Used by the modem to indicate a ring signal from
telephone line
|
|
|
|
To learn more about RS-232, check
out:
RS-232 Tutorial - the basics: Three easy steps to understand and control
your RS232 devices |
|
|
|
|
|
|
Q: |
|
Do I need to use handshake lines to
control the data direction? |
|
|
|
This is not necessary. The converters come with
the Auto-Turn-Around feature, the RS-485 transceiver circuit will change
the data direction automatically upon sensing a "start bit" (a
logic high
"Mark" to
low "Space" transition) from its RS232 data transmit line (TxD). |
|
| |
|
|
|
|
Q: |
|
My control software requires
handshake lines to be tied together (e.g. DTR & DCR, RTS & CTS are
connected). Can I still use your converters? |
|
| |
|
Yes, to satisfy the requirements of some
software, the following handshake lines are tied together in the
converters. |
|
| |
|
- Pin 1 (DCD) is connected to Pin
4 (DTR) and Pin 6 (DCR) |
|
| |
|
- Pin 7 (RTS) is connected to Pin
8 (CTS) |
|
| |
|
Note: Above pin assignments are for DTE
devices |
|
| |
|
|
|
|
Q: |
|
What are the supported Baud Rates? |
|
| |
|
For standard serial converters
(CVT-485-1, CVT-485_422-1, TTL-232-1,
TTL33-232-1 and TTL-485-2), baud rates from
300 to 115,200 bps are supported. For isolated serial converters,
isolators and repeaters
(CVT-485_422-3, CVT-232A-3, CVT-232B-3, RPT-232-3 and RPT-485_422-2), please refer to spec sheets for the supported baud rates.
The converters can auto-detect and self-adjust to the baud rate used
by the serial devices. |
|
| |
|
|
|
|
Q: |
|
Do I need to set the baud rate on the
converters for them to work with different serial devices? |
|
| |
|
This is not necessary, since the
converters can auto-detect and self-adjust to the data format (baud
rate, data bit, parity, stop bit, etc.) used by the serial devices. |
|
| |
|
|
|
|
Q: |
|
Can I use converters to extend the RS-232
data line distance? |
|
| |
|
Yes, the RS-232 data line has a distance
limitation of fifty (50) feet (about 15 m), while the RS-485/RS-422
can go up to 4000 feet (1200 m). It is a common practice to use the
converters to extend the RS-232 data line.
To protect your RS-232 devices from surge voltages while extending the
RS-232 distance, we would recommend the RPT-232-3 - an optically
isolated RS-232 data repeater (extender) (TX, RX, and GND), which works
in pairs to extend the full-duplex RS-232 distance up to 1.8
miles (3 km) @ 300bps baud or 1600 feet (500m) @ 28.8kbps baud.
This product features opto-isolation circuitry, which
effectively protect your RS-232 devices from transient surges,
ground loop, and remote lightning. |
|
| |
|
|
|
|
Q: |
|
What is SMT? What are the benefits of
using a SMT Circuit Card? |
|
|
|
SMT stands for Surface Mount Technology.
Our converters use SMT circuits, thus the current consumption is very small
(less than 10mA), while other Discrete Component type of converters in
the market consume much more power - normally between 50mA to 100mA.
Less current generates less heat, hence, the converters last longer. |
|
| |
|
|
|
|
Q: |
|
What is the current consumption of
your converters? |
|
| |
|
Our port-powered converters consume less than 10mA of
current. |
|
| |
|
|
|
|
Q: |
|
What is the maximum distance the
converters can communicate with remote devices? |
|
| |
|
Depending on the power from RS-232 port, the
RS232/RS485/RS422 converters can go up to 4000 feet
(1200 m) for the maximum baud rate of 19200 bps. |
|
|
|
|
|
|
Q: |
|
How many serial devices can I connect
with the port-powered converters? |
|
|
|
For standard serial converters
(CVT-485-1, CVT-485_422-1 and TTL-485-2), you can connect a maximum of 128 serial
devices (RS-485 or RS422); for isolated serial converters
(CVT-485_422-3), you can connect a maximum of 64 serial devices
(RS-485 or RS422). However, this depends a great deal on a few factors such as
the RS-485/RS-422 devices connected to the converter, data baud rate,
cable distance, etc. |
|
| |
|
|
|
|
Q: |
|
When do I need to
turn ON the terminator (120Ω
End-of-Line Resistor)? |
|
| |
|
Turn ON the
Terminator - End of Line Resistor
(120Ω), to prevent interference on the data line.
However, since the Terminator will increase the load on
the data circuit, we recommend to turn ON the Terminator only when
data rate is over 19,200bps or when the distance exceeds 660 feet (200m). |
|
| |
|
|
|
|
Q: |
|
Which type of cable is recommended for
RS-485 / RS-422 connections? |
|
| |
|
Inexpensive Cat 5
shielded cables (STP - shielded twisted pair)
generally exceed the recommendations for RS-422 (although its
characteristic impedance is 100Ω rather than the
required 120Ω). This makes it an
excellent choice for RS-485 and RS-422 systems. |
|
| |
|
|
|
|
Q: |
|
What is GND? Can I connect it to the
Earth? |
|
|
|
GND on the converters is the Signal Ground. Do NOT connect GND to
the Earth. |
|
| |
|
|
|
|
Q: |
|
What is a Static Protection
Circuit? Is it a Surge Suppressor? |
|
|
|
The Static Protection Circuit is also
called an ESD (Electro-Static Discharge). The charged
capacitance of a human body enables a person to destroy integrated
circuits with a single touch. Such a contact can easily occur during
the installation of an interface cable. To prevent ESD damage, the
converters come with the protection circuit to protect RS-422/RS-485
transceivers against ESD levels for up to ±15kV.
Static Protection Circuit is NOT a Surge Suppressor. If the
converters are to be connected to outdoor devices, to prevent your PC
or other devices from being damaged by lightning strikes, proper
lightning protection, opto-isolated converter (e.g. CVT-485_422-3) or
isolator (e.g. CVT-232A-3 or CVT-232B-3) is required. |
|
|
|
|
|
|
Q: |
|
What is
Opto-isolation? What are the benefits of using Opto-isolated
converters? |
|
|
Opto-isolation uses optical isolators to
isolate two serial devices. Optical isolator is a common element used
for asynchronous data applications such as RS-232, RS-485 and RS-422
systems. With an optical isolator, only light passes between two
serial devices, this is performed with an LED and a photosensitive
transistor. There are many
benefits of using opto-isolated converters, most importantly, it
protects your RS-232 devices from transient surges, ground loop, and
remote lightning effectively.
Optical isolation also eliminates ground loop and noise problems
because the ground of two connected devices are separated. |
| |
|
|
|
|
|
|
Q: |
|
What are the
differences of using Surge Suppressors and Opto-Isolators? |
|
|
Typical surge suppressors use
special diodes to shunt excess energy to ground. It requires high
installation quality because an extremely low impedance ground
connection must be provided to handle this energy. Opto-isolation, on
the other hand, does not require an additional ground connection,
making it insensitive to installation quality. Furthermore, for
opto-isolation, as there is no current flowing through the two
connected serial devices, equipment are better protected for high
current and voltage drops.
Please note that
opto-isolation is not a perfect solution. The isolation voltages are
limited (typically range from 500V to 4000V), and an additional power
supply or an isolated DC-DC converter is required to support the
circuitry. In some cases,
applying both isolation and surge suppression provides better
protection for your serial devices. |
| |
|
|
|
|
|
|
Q: |
|
Will the converters work with new
computers? |
|
|
|
Yes, our converters work well with new
computers, which normally come with lower
power RS232 COM ports (around
-8VDC
compared to -12VDC
of "old" computers). |
|
| |
|
|
|
|
Q: |
|
Will the converters work with USB to
RS-232 Cables/Converters? |
|
|
|
Most of modern computers (especially Laptops) do NOT come with RS-232
COM ports, therefore USB to RS-232 Cables / Converters (which creates
a Virtual COM port on the PC) are widely used. We have tested our
converters with many kinds of USB to RS-232 Cables / Converters
available in the market. There is no problem using
our converters with USB to RS-232 Cables / Converters. However,
if you found your USB/RS232 converters/cables do not work with our
converters, please drop us a mail. Thank you! |
|
| |
|
|
|
|
Q: |
|
Can I use your converters without
using the terminal block provided? |
|
|
|
No problem. For your convenience, we provide a
terminal block with each converter, which is useful as you can connect
the RS-485/RS-422 cables directly into the terminal block without
making your own connector.
You can also use the converters without the terminal block, as it is
merely a
conversion from DB9 to Screw Terminals, with some jumpers on the
circuit board. In case you need to make you own connections without
using the terminal block, please refer to the Pin Assignment on the
spec sheet for detailed connections. |
|
| |
|
|
|
|
Q: |
|
How do I use CVT-485_422-1
/ CVT-485_422-3 as a
RS-232/RS-422 converter? |
|
|
|
CVT-485_422-1 and CVT-485_422-3 are dual-function
converters, so they can be used to convert any standard RS-232 port into
a two-wire half-duplex RS-485 port, or a four-wire full-duplex RS-422
port and vice versa. This is done through the Jumper settings on the
terminal block. For example: Jumper 1, 2 & 3 are ON (shorted) by
default, which is used for RS-232/RS-485 conversion. When all three
jumpers are removed (opened), it becomes a RS-232/RS-422 converter. |
|
|
|
|
|
|
Q: |
|
How do I perform a Loopback Test for
my RS-232/RS-485 converter? |
|
|
|
It is a simple task to perform a Loopback
Test with CommFront's 232Analyzer
software: connect two RS-232/RS-485 converters
to your PC's COM ports (if your PC does not have enough COM ports, you may use
USB to RS-232 converters or cables). Run two instances of
232Analyzer software on your PC. When you send commands
(i.e. "CommFront" in ASCII format) from one
COM port, you should receive the same commands on the other, and vice
versa. |
|
| |
|
By performing a simple Loopback Test
like this, you can test you RS-485 transceiver, which is very helpful
when you are in doubt about the performance of your converters or
cables. |
|
|
|
|
|
|
|
Click
here
to download a FREE copy of 232Analyzer software. |
|
| |
|
|
|
|
Q: |
|
How do I perform a Loopback Test for
my
RS-232/RS-422 converter? |
|
| |
|
Performing a Loopback Test is easy with
CommFront's 232Analyzer
software. Simply connect TX+ and TX- to RX+ and RX-
respectively (or remove Jumper 1 and terminate Jumper 2 & 3 on the
termination board provided) and connect the RS-232/RS-422 converter to your PC's COM
port. Launch 232Analyzer
software and open the COM port. Key in some test
commands (i.e. "CommFront" in ASCII format) in the Send_Command_Pane, then click on the
"Send" button, in the Logging window, you should get an echo (i.e.
"CommFront" in ASCII format) of the commands sent.
By performing a simple Loopback Test like this, you can test both the
Transmitter and Receiver of your RS-232/RS-422 converter, which is
very helpful when you have questions about the performance of your
converters or cables. |
|
|
|
|
|
|
|
Click
here
to download a FREE copy of 232Analyzer software. |
|
| |
|
|
|
|
Q: |
|
How do I perform a Loopback Test for
my RS-232/TTL converter |
|
|
It is a simple task to perform a Loopback
Test with CommFront's 232Analyzer
software, simply connect TX (TTL out) to RX (TTL in) and then send commands
from the 232Analyzer software (i.e. "CommFront" in ASCII format), you should receive
an echo of the commands sent. |
|
|
By performing a simple
Loopback Test like this, you can test both the transmitter and
receiver of your RS-232/TTL converter, which is very helpful when
you are in doubt about the performance of your converter. |
| |
|
|
|
Q: |
|
How do I perform a Loopback Test for
my RS-232 COM port? |
|
|
|
Loopback Test provides an effective way
to test your RS-232 COM ports or cables. By using CommFront's
232Analyzer software, you can test both your RS-232 COM ports and
cables: |
|
| |
|
If you are testing your RS-232 COM port,
simply connect Pin 2 to 3 of your DB9 connector (connecting RX to TX),
then run the 232Analyzer
software and send commands from the Send_Command_Pane,
you should receive an echo of the commands sent. |
|
| |
|
If you are communicating with a remote
RS-232 device, run the 232Analyzer
software on both ends of the PC and turn ON/OFF the line
state or send commands from one end, and you should be able to see the
changes or receive the commands on the other end. |
|
|
|
By performing a simple
Loopback Test like this, you can test both the RS-232 COM port and
cable, which is very helpful when you have doubts about the
performance of your COM ports or cables. |
|
|
|
|
|
|
|
Click
here
to download a FREE copy of 232Analyzer software. |
|
| |
|
|
|
|
Q: |
|
Can I use more than
one RPT-485_422-2 to extend the RS-485/422 distance? |
|
|
|
It is not recommended to use more than
one RPT-485_422-2 for extending the RS-485/RS-422's distance. If
your project requires more than 8000 feet (2.4km) for the
RS-485/RS-422 distance, please use fiber optic products. |
|
| |
|
|
|
|
Q: |
|
What is the maximum
number of supported nodes in a RS-485/RS-422 circuit if the
RPT-485_422-2 is used? |
|
|
|
The maximum number of supported nodes in
a RS-485/RS-422 circuit depends on the RS-485/RS-422 master, for
example, if the RS-485 master supports only 32 nodes, the maximum
number of supported nodes in the RS-485 network is 32. The use of
RPT-485_422-2 only extends the RS-485/RS-422 distance, it will not
affect the total number of nodes that can be used in the circuit.
|
|
| |
|
|
|
|
Q: |
|
What should I know about the Product
Warranty? |
|
|
|
All CommFront hardware products come
with a two-year workmanship warranty. |
|
| |
|
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| |
