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Q: |
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How do the RS232/TTL converter
derive power? Do I need to turn ON DTR or RTS in order to power the
converter? |
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Q: |
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How do I know the RS232/TTL
converter is powered and functioning well? |
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Q: |
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The RS232/TTL converter is
port-powered. Why is there a +5V sign on the converter? Can I connect
external power to this terminal? |
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Q: |
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Can I plug / unplug the
converters while they are being used? |
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Q: |
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What is DTE / DCE? How do I
know my RS-232 Device is a DTE or a DCE? |
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Q: |
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What are Handshake Lines? |
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Q: |
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Do I need to use handshake
lines to control the data direction? |
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Q: |
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My control software
requires handshake lines to be tied together (e.g. DTR & DCR, RTS &
CTS). Can I still use your RS232/TTL converter? |
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Q: |
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What are the supported Baud
Rates? |
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Q: |
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Do I need to set the baud rate
on the converters for them to work with different serial devices? |
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Q: |
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Can I use your RS485/TTL converter to
extend the TTL distance? |
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Q: |
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What is SMT? What are the
benefits of using a SMT Circuit Card? |
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Q: |
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What is the current
consumption of your TTL converters? |
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Q: |
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What is the maximum
distance the TTL converters can communicate with remote devices? |
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Q: |
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How many serial devices
can I connect with the RS485/TTL converter? |
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Q: |
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When do I need to turn ON the terminator
(End of Line Resistor -120Ω)? |
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Q: |
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What type of cable is
recommended for RS-485/RS-422 connections? |
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Q: |
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What is GND? Can I connect
it to the Earth? |
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Q: |
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What is a Static
Protection Circuit? Is it a Lightning Arrestor? |
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Q: |
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Will the RS232/TTL converter work
with new computers? |
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Q: |
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Will the RS232/TTL converter work
with USB to RS-232 Cables/Converters? |
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Q: |
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Can I use your converters
without using the terminal block provided? |
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Q: |
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How do I perform a
Loopback Test for my RS-232/TTL converter? |
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Q: |
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What should I know about
the Product Warranty? |
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Q: |
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How do the RS232/TTL converter derive power?
Do I need to turn ON DTR or RTS in order to power the converter? |
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The RS232/TTL converter is 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. |
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Q: |
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How do I know the
RS232/TTL converter is
powered and functioning well? |
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There is a +5V pin on the termination board attached to the
converter (for TTL-232-1 only). 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. |
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Q: |
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The RS232/TTL is port-powered. Why
is there a +5V sign on the converter? Can I connect external power to
this terminal? |
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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 converter is 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). |
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Q: |
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Can I plug / unplug the converters
while they are being used? |
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Yes, the converters come with a Data
Transceiver Protection Circuit (to protect the Data Transceiver inside
the converter) and therefore are hot-pluggable. |
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Q: |
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What is DTE / DCE? How do I know my
RS-232 Device is a DTE or a DCE? |
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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: |
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>> 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.
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To learn more about
RS-232, check out:
RS-232 Tutorial - the basics: Three easy steps to understand and control
your RS232 devices |
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Q: |
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What are Handshake Lines? |
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Handshake Lines are used to control the
direction of data flow between DTE and DCE. They are: |
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RTS (Request to Send) - Asserted by DTE to prepare DCE to receive
data. |
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CTS (Clear to Send) - RTS Acknowledgment by DCE to allow DTE to
transmit. |
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DTR (Data Terminal Ready) - Asserted by DTE to indicate that it is
ready to be connected. |
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DSR (Data Set Ready) - Indicates an
active connection by DCE. |
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DCD (Data Carrier Ready) - Used by modem
when a connection has been established with remote equipment. |
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RI (Ring Indicator) - Used by the modem to indicate a ring signal from
telephone line
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To learn more about RS-232, check
out:
RS-232 Tutorial - the basics: Three easy steps to understand and control
your RS232 devices |
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Q: |
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Do I need to use handshake lines to
control the data direction? |
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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). |
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Q: |
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My control software requires
handshake lines to be tied together (e.g. DTR & DCR, RTS & CTS are
connected). Can I still use your RS232/TTL converter? |
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Yes, to satisfy the requirements of some
software, the following handshake lines are tied together in the
RS232/TTL converter. |
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- Pin 4 (DTR) is connected to Pin 6 (DCR) |
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- Pin 7 (RTS) is connected to Pin
8 (CTS) |
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Note: Above pin assignments are for DTE
devices |
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Q: |
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What are the supported Baud Rates? |
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Baud Rates from 300 to 115,200 bps are
supported. The TTL converters can auto-detect and self-adjust to the baud
rate used by the serial devices. |
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Q: |
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Do I need to set the baud rate on the
converters for them to work with different serial devices? |
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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. |
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Q: |
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Can I use your
RS485/TTL converter to extend the TTL distance? |
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Yes, the TTL signal has a distance
limitation of ten (10) feet (about 3 m), while the RS-485 can go up to 4000 feet
(1200 m). It is a common practice to use the RS485/TTL converter to extend the
TTL distance. |
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Q: |
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What is SMT? What are the benefits of
using a SMT Circuit Card? |
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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. |
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Q: |
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What is the current consumption of
your TTL converters? |
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The port-powered RS232/TTL converter
consumes less than 10mA of current, while the RS485/TTL converter
consumes less than 30mA of current. |
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Q: |
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What is the maximum distance the
TTL converters can communicate with remote devices? |
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TTL signal has a distance limitation of
ten (10) feet (about 3m), while RS232 can go up to fifty (50) feet
(about 15m), and RS485/RS422 signals can go up to 4000 feet
(1200 m) for the maximum baud rate of 19200 bps. |
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Q: |
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How many serial
devices can I connect with the RS485/TTL converter? |
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You can connect a maximum of 128 serial
devices on RS485 side. 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. |
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Q: |
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When do I need to turn ON the
terminator (End of Line Resistor -120Ω)? |
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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). |
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Q: |
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Which type of cable is recommended for
RS-485 / RS-422 connections? |
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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. |
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Q: |
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What is GND? Can I connect it to the
Earth? |
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GND on the converters is the Signal Ground. Do NOT connect GND to
the Earth. |
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Q: |
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What is a Static Protection
Circuit? Is it a Lightning Arrestor? |
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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 Lightning Arrestor. 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 is required. |
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Q: |
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Will the RS232/TTL converter work with new
computers? |
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Yes, our port-powered RS232/TTL converter works well with new
computers, which normally come with lower
power RS232 COM ports (around
-8VDC
compared to -12VDC
of "old" computers). |
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Q: |
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Will the RS232/TTL converter work with USB to
RS-232 Cables/Converters? |
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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! |
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Q: |
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Can I use your converters without
using the terminal block provided? |
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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. |
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Q: |
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How do I perform a Loopback Test for
my RS-232/TTL converter? |
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It's
a simple task to perform
a Loopback test by using CommFront’s 232Analyzer
software: Connect TX
(TTL Out) to RX (TTL In), and then send commands from the 232Analyzer
software. You should get an echo of the commands sent.
By performing a simple Loopback test like this, you can test both the
Transmitter and Receiver of the RS-232/TTL converter. This is very
helpful when you are in doubt about the performance of your converter. |
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Click
here
to download a FREE copy of 232Analyzer software. |
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Q: |
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What should I know about the Product
Warranty? |
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All CommFront hardware products come
with a two-year workmanship warranty. |
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