COM Port Connection

[Guest Elias]

Dear Experts. I connected my laptop to an STB (Receiver) through an RS232

cable. I need to check if the connection is established through the serial

COM1 port to the STB. Is there any way/command that i can use to check that

the PC is actually connected to the STB?

 

Thanks.

Elias

[Guest John McGaw]

Re: COM Port Connection

 

Elias wrote:

> Dear Experts. I connected my laptop to an STB (Receiver) through an RS232

> cable. I need to check if the connection is established through the serial

> COM1 port to the STB. Is there any way/command that i can use to check that

> the PC is actually connected to the STB?

>

> Thanks.

> Elias

 

One of the many free terminal emulator programs should do the job.

[Guest Elias]

Re: COM Port Connection

 

Can you elaborate please? excuse my ignorance, but i installed one "terminal

emulator" software that i dont know what is it to start with, and i didnt

know where to go from there. can you please explain a bit further?

 

Thanks

 

"John McGaw" wrote:

> Elias wrote:

> > Dear Experts. I connected my laptop to an STB (Receiver) through an RS232

> > cable. I need to check if the connection is established through the serial

> > COM1 port to the STB. Is there any way/command that i can use to check that

> > the PC is actually connected to the STB?

> >

> > Thanks.

> > Elias

>

> One of the many free terminal emulator programs should do the job.

>

[Guest Pegasus \(MVP\)]

Re: COM Port Connection

 

Under a terminal emulator (e.g. HyperTerminal) you can nominate

the COM port you wish to talk to. When a serial device (e.g. an

ordinary modem) is connected to that port then your keystrokes

are echoed on the terminal emulator screen. Otherwise, nothing

happens.

 

 

"Elias" <Elias@discussions.microsoft.com> wrote in message

news:B97D8E45-7AFF-4866-80E4-5ED96D7CDA9D@microsoft.com...

> Can you elaborate please? excuse my ignorance, but i installed one

> "terminal

> emulator" software that i dont know what is it to start with, and i didnt

> know where to go from there. can you please explain a bit further?

>

> Thanks

>

> "John McGaw" wrote:

>

>> Elias wrote:

>> > Dear Experts. I connected my laptop to an STB (Receiver) through an

>> > RS232

>> > cable. I need to check if the connection is established through the

>> > serial

>> > COM1 port to the STB. Is there any way/command that i can use to check

>> > that

>> > the PC is actually connected to the STB?

>> >

>> > Thanks.

>> > Elias

>>

>> One of the many free terminal emulator programs should do the job.

>>

[Guest Elias]

Re: COM Port Connection

 

ok, great, now we're going somewhere, but what if the device connected to the

port does not have a keyboard, then how can i check if it is connected? you

said that the keystrokes are echoed on the therminal emulator screen, you

mean which keystrokes? strokes on my pc keyboard? i have to type something on

my pc keyboard and if the other device is connected, then i have to see the

keystrokes on the screen of the emulator?

 

Thanks,

 

"Pegasus (MVP)" wrote:

> Under a terminal emulator (e.g. HyperTerminal) you can nominate

> the COM port you wish to talk to. When a serial device (e.g. an

> ordinary modem) is connected to that port then your keystrokes

> are echoed on the terminal emulator screen. Otherwise, nothing

> happens.

>

>

> "Elias" <Elias@discussions.microsoft.com> wrote in message

> news:B97D8E45-7AFF-4866-80E4-5ED96D7CDA9D@microsoft.com...

> > Can you elaborate please? excuse my ignorance, but i installed one

> > "terminal

> > emulator" software that i dont know what is it to start with, and i didnt

> > know where to go from there. can you please explain a bit further?

> >

> > Thanks

> >

> > "John McGaw" wrote:

> >

> >> Elias wrote:

> >> > Dear Experts. I connected my laptop to an STB (Receiver) through an

> >> > RS232

> >> > cable. I need to check if the connection is established through the

> >> > serial

> >> > COM1 port to the STB. Is there any way/command that i can use to check

> >> > that

> >> > the PC is actually connected to the STB?

> >> >

> >> > Thanks.

> >> > Elias

> >>

> >> One of the many free terminal emulator programs should do the job.

> >>

>

>

>

[Guest Paul]

Re: COM Port Connection

 

Elias wrote:

> ok, great, now we're going somewhere, but what if the device connected to the

> port does not have a keyboard, then how can i check if it is connected? you

> said that the keystrokes are echoed on the therminal emulator screen, you

> mean which keystrokes? strokes on my pc keyboard? i have to type something on

> my pc keyboard and if the other device is connected, then i have to see the

> keystrokes on the screen of the emulator?

>

> Thanks,

>

 

First of all, you should find a manual for your STB. I can see a problem

right away, by looking at this. This would be an example of a manual.

 

http://www.sbcatest.com/TechUpdates/DTV-MD-0058-DIRECTV%20Set-top%20Information%20for%20Installers-V2.0.pdf

 

The manual shows 8 bit codes being used for the commands. The

ASCII character set is encoded in 7 bit codes. Now, the

people who invented the protocol, on that example STB,

set the upper bit in the code. And I would guess, the

purpose is to prevent people from using Hyperterminal

to talk to their STB :-) At least some of the

returned codes are also 8 bit, and would display as

garbage on the Hyperterminal screen.

 

In short, the protocol is not intended to be human readable,

unlike the protocol used on a modem (where at least a few

things you do, are human readable, and fun to play with).

 

Seriously, you should be using a software intended for "talking"

to the STB. If that software cannot establish a connection,

then either the baud rate or similar setting is wrong, or

the type of RS-232 cable needs to be changed. RS-232 cables

are either straight through, or a null modem type cable, swaps

some signals. RS-232 is not supposed to be damaged, by

connecting a transmitter signal to a transmitter signal,

so you can try both types of cables, if the manual

doesn't happen to mention whether the STB is DTE or DCE.

My assumption is they'd set it up so it uses a straight

cable from the computer to the STB, and I have a 50:50

chance of being right :-)

 

So you can connect a cable, between the PC and the STB,

run Hyperterminal, select the correct COM port, and start

typing. But the STB will be silent in return, because

it is expecting 8 bit codes with the upper bit set. It'll

have nothing to say.

 

You need keys on the keyboard, that generate codes having

decimal values higher than 127. Can you see yourself

typing "heart symbol" which is decimal 169 or hex 0xA9 ?

That protocol was designed for a computer program to drive.

There is no "heart" on my keyboard.

 

http://casa.colorado.edu/~ajsh/iso8859-1.html

 

This is an example of a software designed to do stuff

to a set top box. On one of their web pages, they

mention "irreversible damage" to the STB, as one outcome

of screwing with it. Like if you load the wrong firmware.

 

http://www.dmsiusa.com/documents/PCLink2.33U.pdf

 

I think you really need to visit a site that specializes in

hacking STBs, as someone will have already done whatever you're

trying to do, and they could save you a lot of grief and

wasted time.

 

HTH,

Paul

[Guest Elias]

Re: COM Port Connection

 

Thanks Paul, the issue is that i downloaded the software to upload the new

firmware for my STB but that one is freezing. So i thought that maybe i am

using the wrong cable, hence i opened this question, wanted to make sure that

the STB is listening and the cable i am using is correct. i am using an

RS-232C cable (male DB25 to Female DB9)

 

All what is says on the manual of the STB is: 9pin D-Sub RS232C, Baud

Rates:115200baud max.

 

Seems that i can not check it this way?

 

Thanks again.

 

"Paul" wrote:

> Elias wrote:

> > ok, great, now we're going somewhere, but what if the device connected to the

> > port does not have a keyboard, then how can i check if it is connected? you

> > said that the keystrokes are echoed on the therminal emulator screen, you

> > mean which keystrokes? strokes on my pc keyboard? i have to type something on

> > my pc keyboard and if the other device is connected, then i have to see the

> > keystrokes on the screen of the emulator?

> >

> > Thanks,

> >

>

> First of all, you should find a manual for your STB. I can see a problem

> right away, by looking at this. This would be an example of a manual.

>

> http://www.sbcatest.com/TechUpdates/DTV-MD-0058-DIRECTV%20Set-top%20Information%20for%20Installers-V2.0.pdf

>

> The manual shows 8 bit codes being used for the commands. The

> ASCII character set is encoded in 7 bit codes. Now, the

> people who invented the protocol, on that example STB,

> set the upper bit in the code. And I would guess, the

> purpose is to prevent people from using Hyperterminal

> to talk to their STB :-) At least some of the

> returned codes are also 8 bit, and would display as

> garbage on the Hyperterminal screen.

>

> In short, the protocol is not intended to be human readable,

> unlike the protocol used on a modem (where at least a few

> things you do, are human readable, and fun to play with).

>

> Seriously, you should be using a software intended for "talking"

> to the STB. If that software cannot establish a connection,

> then either the baud rate or similar setting is wrong, or

> the type of RS-232 cable needs to be changed. RS-232 cables

> are either straight through, or a null modem type cable, swaps

> some signals. RS-232 is not supposed to be damaged, by

> connecting a transmitter signal to a transmitter signal,

> so you can try both types of cables, if the manual

> doesn't happen to mention whether the STB is DTE or DCE.

> My assumption is they'd set it up so it uses a straight

> cable from the computer to the STB, and I have a 50:50

> chance of being right :-)

>

> So you can connect a cable, between the PC and the STB,

> run Hyperterminal, select the correct COM port, and start

> typing. But the STB will be silent in return, because

> it is expecting 8 bit codes with the upper bit set. It'll

> have nothing to say.

>

> You need keys on the keyboard, that generate codes having

> decimal values higher than 127. Can you see yourself

> typing "heart symbol" which is decimal 169 or hex 0xA9 ?

> That protocol was designed for a computer program to drive.

> There is no "heart" on my keyboard.

>

> http://casa.colorado.edu/~ajsh/iso8859-1.html

>

> This is an example of a software designed to do stuff

> to a set top box. On one of their web pages, they

> mention "irreversible damage" to the STB, as one outcome

> of screwing with it. Like if you load the wrong firmware.

>

> http://www.dmsiusa.com/documents/PCLink2.33U.pdf

>

> I think you really need to visit a site that specializes in

> hacking STBs, as someone will have already done whatever you're

> trying to do, and they could save you a lot of grief and

> wasted time.

>

> HTH,

> Paul

>

[Guest Paul]

Re: COM Port Connection

 

Elias wrote:

> Thanks Paul, the issue is that i downloaded the software to upload the new

> firmware for my STB but that one is freezing. So i thought that maybe i am

> using the wrong cable, hence i opened this question, wanted to make sure that

> the STB is listening and the cable i am using is correct. i am using an

> RS-232C cable (male DB25 to Female DB9)

>

> All what is says on the manual of the STB is: 9pin D-Sub RS232C, Baud

> Rates:115200baud max.

>

> Seems that i can not check it this way?

>

> Thanks again.

>

 

The thing is, if you are debugging a modem connected via RS-232, the

interface uses printable characters. Then, if you start the Hyperterminal

program, that is designed to work with printable characters. You can

use the keyboard to send commands, and you see "OK" come back from the modem.

 

The problem I see, is the STB is using non-printable characters. Those

are going to be more of a problem to generate. And if the STB sends back

non-printable responses, you have a similar problem checking the response

that comes back.

 

Download this. Place the download in a separate folder. Double click to

extract. There is "setup.exe". Double click to install. Then look in

Start:Programs:B&B Electronics for the program to run. it is called

COMTest. You get to specify a COM port, like COM1, then select baud

rate and the rest. I'd try powering off the STB, power on, and perhaps

it will autobaud or play nice at 9600. Use the settings in the DirectTV

manual as a guide.

 

http://www.bb-elec.com/bb-elec/software/comtest/com_test.exe

 

Some info on COM_Test here.

 

http://www.bb-elec.com/tech_articles/econn_check_2wire_rs485.asp

 

"Option for Sending Unprintable Characters -

Alt + 3 digit scancode, then release Alt"

 

What they don't tell you, is that the numbers must be entered

on the numeric keypad (right hand side) of the keyboard, and not the

normal numbers. The number entered is a "scancode", and appears to get

translated (which sucks). So far, I'm not making much headway, on figuring

out how the translation works.

 

By walking through the possible values, one at a time, I've determined

that typing (hold down alt) 1 5 9, gives <83> or 0x83 hexidecimal,

on the COMtest screen. That <??> value would be the hexidecimal value

sent to the port. Your mapping may be different than mine, because it

is a keyboard translation table of some sort.

 

I would disconnect the STB, before evaluating scancode values. Maybe

you'll get lucky, and alt 159 will give <83>.

 

On the DirectTV STB, <83> is GetPrimaryStatus, and dumps a small table

of information. I'm hoping a command like that would be safe enough, to

issue again and again. Be careful, as you could brick it...

 

If there are no standards for STBs, the command set could be different

on each one.

 

Good luck,

Paul