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Many times it's very handy to have a LED (a small light) on or flashing to
indicate when your BMI receiver box is transmitting. This is especially
the case with BMI cable where interruptions in transmission are not
infrequent. An RS-232 "Break-out Box" from BB Electronics is very handy
to visually monitor the transmission from your receiver box, before it even
gets to your PC. The RS-232 Break-out Box is actually a small RS-232
device that is inserted between your receiver box and the serial port on
your PC. I keep my Break-out Box right beside my Monitor for
TradeStation.
LED's in the Break-out Box indicate which RS-232 Pins are active. In the
case of BMI cable, Pin 3 is all that matters. A Red LED in the Break-out
Box indicates whether data is being transmitted in Pin 3. Therefore with
a quick glance at the LED for Pin 3, I know if I'm receiving data from the
Receiver box. However if I see only an occasionally flash form the Pin 3
LED, then the BMI receiver isn't transmitting at all and it's time to
re-configure the receiver.
Further if I see the LED for Pin 3 is on constantly then I know that the BMI
transmission is maxed out and I likely have delays in the BMI data.
Normally the Pin 3 LED is blinking indicating that BMI is not transmitting
at full capacity and therefore the BMI data is likely as current as BMI
gets. Generally BMI is always "maxed out" right after 9:30 AM ET and
usually right after 3:00 PM ET, plus any other time during the day where
there's heavy volume.
The fact that the BMI transmission is still "maxed out" occasionally in
spite of dropping Canadian data, international data, some Forex and perhaps
some option information indicates how much BMI transmission is affected by
having a single 38 K feed. I've suggested BMI add a second 38 K feed, but
have been ignored.
The RS-232 Break-out box was designed so you can turn off and on certain
RS-232 Pins and cross-wire Pins. That's not of any use with the BMI feed,
so it's only the LED's in the Break-out Box that are useful. The
Break-out Box costs $34.95 plus shipping. The web page link is
http://www.bb-elec.com/product.asp?dept%5Fid=22&sku=232BOB1
The rest of this post concerns how to select the correct RS-232 cables to
hook in the Break-out Box between the Receiver and your PC port.
SELECTING RS-232 CABLES
The B&B Electronics Break-out box has a 25-pin Female RS-232 (serial)
connector on one end and a Male 25-pin RS-232 connector on the other end.
The primary problem is getting the correct type of RS-232 cable to connect
the receiver box to the Male 25-pin connector on the Break-out Box, and then
a RS-232 cable to connect the PC serial port to the 25-pin Female Connector
on the break-out Box.
For example where my BMI cable receiver has a 9-pin Female RS-232 connector,
I use a RS-232 cable with a 9-pin Male connector on one end and a 25 pin
Female connector on the other end to connect the Receiver Box to the
Break-out Box. Then I need a RS-232 cable with a 25-pin Male connector (to
connect to the Female 25-pin connector on the Break-out box) and the other
end of the cable needs the correct connector to connect to whichever serial
port you use on your PC.
PC shops normally carry a number of RS-232 cables with different connectors
so it's important to figure out ahead of time what type of connectors your
need on your RS-232 cables, as well as the length.
For background B&B Electronics specializes in RS-232 devices and software.
They seem to have excellent service. RS-232 seems to be used extensively
for engineering purposes to receive data from and control instruments.
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