can any logic expert help?

hey

i have an ntp 377-200 multichannel meter. its a modular system that can display meters for 8-40 chs. i bought a 16ch version on ebay and two more additional cards from another source - assuming i could just plug them in and thereby extend the system. but now it looks like that wont work :-( supposedly the channel count information is programmed into prom's.
is there any chance one could change the channel count still? i have no clue about this kind of stuff. but could one read the prom's and write new ones or something like that?
i attached the documents i have and would greatly appreciate any help!

thanks a lot
jakob

ps: the info is on page 5

salomonander said:

...........but could one read the prom's and write new ones or something like that? ............

thanks a lot
jakob

ps: the info is on page 6

Click to expand...

Hi Jacob,

I am certainly not a logic expert but if the PROM is not read protected then with (quite) a bit of work one can read the machine code. And that is neither useful (unless you want to copy it) nor exiciting to look at. It is not  the source code where you can make sense of what's going on.

If the system is designed for up to 40 channels then I would expect that it would be selectable through either on board jumpers or microswitches. I don't thin they would do seperate versions for various channel options.

sahib said:

salomonander said:

...........but could one read the prom's and write new ones or something like that? ............

thanks a lot
jakob

ps: the info is on page 6

Click to expand...

Hi Jacob,

I am certainly not a logic expert but if the PROM is not read protected then with (quite) a bit of work one can read the machine code. And that is neither useful (unless you want to copy it) nor exiciting to look at. It is not  the source code where you can make sense of what's going on.

If the system is designed for up to 40 channels then I would expect that it would be selectable through either on board jumpers or microswitches. I don't thin they would do seperate versions for various channel options.

Click to expand...

Hey Sahib

how are you? did you have a chance to look at the manual? i read through it but couldn't find any info on a way to select the channel count. maybe i missed something... as you have said it doesnt make much sense that they would programm each version differently. the original broshure says its expandable up to 40ch also. but i couldnt find anything in the documents im afraid.

ps: the manual says:
"the information about how many channels the instrument is equiped with, and how the different scale/channel layouts are defined, are programmed in a set of three PROM's"    - sounds like bad news - or am i wrong?

Hi Jacob,

Not too bad, thank you.

I can't see sufficient information on those data sheets either but it is still strange.

On remote control connector  pin 20a and 21a are channel select (page 1) and  10 to 14 are card select (page 2). So, one would assume that as soon as you plugged in the remote control all of the card selects would be activated. You do not mention the remote control. Do you have it? If you do not, can you check how the first two cards (16 channel) are activated? The data sheet says the ports are normally closed. I am not sure what they mean. Whether you pull them down to activate them. If that is the case then it would solve your problem.

sahib said:

Hi Jacob,

Not too bad, thank you.

I can't see sufficient information on those data sheets either but it is still strange.

On remote control connector  pin 20a and 21a are channel select (page 1) and  10 to 14 are card select (page 2). So, one would assume that as soon as you plugged in the remote control all of the card selects would be activated. You do not mention the remote control. Do you have it? If you do not, can you check how the first two cards (16 channel) are activated? The data sheet says the ports are normally closed. I am not sure what they mean. Whether you pull them down to activate them. If that is the case then it would solve your problem.

Click to expand...

Hey Sahib
no i dont have a remote. actually i dont think there is one. one just has to build it - i have certainly never seen one anywhere. not even in the ntp catalog.
pin 20a and 21a seem to select the channel that is put into the optional analyzer card - which is not installed in my unit. 10-14 seem  to deactive the cards. as soon as i pull them to ground the cards channels are not showing any peak information.
guess im just stuck here and the manual is right about that the channel number is programmed into the proms.

now after playing with it for an hour i think i foud a way to cheat it
when connecting pin 12 or 13 to ground it actually puts me in the analyzer mode (although no anlayze card is installed). instead of showing me a frequncy plot the screen acts as a normal peak meter. i only have 29 channels instead of 32. but my additional cards are working in this screen and all channels seem to show correct vu. this is weired but good news. most functions such as channel highlightning etc also work as they should.
ig downside is that none of the channel labeling is correct. channel 1 is labeled 25hz up to ch 29 which is called 16k i might just stick a piece of tape on my monitor and write the correct channel names on there. at least i have 29 channels nów instead of 16. which is enough.

It is utterly strange.  Pin 15a is indicated as Analyser Mode select.

However, if the other cards are working in the analyser mode then the firmware includes the whole range, not only 16 channels.

Anyhow, at least you got it working in some way.