I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to)

What's the most efficient method (other than brute force) to try all the possible permutations of:

• Baud rate
• Data bits
• Stop bits
• Parity
• Flow control

What I'm really hoping is one of the following:

1. Do all settings matter? (If you can tell me that some settings are optional I don't even have to permutate those in my trial and error)
2. Do some settings give me an indication that I'm on the right track (for example I got partial output on baud rate 9600 - continuous solid white squares that looks like ascii 178 .. by the way how do I know what I'm getting in Putty other than visually trying to match it to ASCII table? Is there a better tool that displays the raw bits coming in?
3. Some other tricks that will help me figure it out (Ex. I'm using putty on windows right now, but maybe there is linux script that can connect to all different permutations one by one?)
4. Some "smell" that tells me about what to try next. Ex. Let's say I get output that scrambled in a particular way, what does that tell me that I need to try next?
5. Relationship between settings and input/output functionality. (For example, my attempt with 9600 bauds gave me that scrambled output upon hitting the enter key - but only once. After that I had to reboot the device to see that again. It's almost as though input stopped working after the first try. Does that tell me anything?)
6. Anything else that can help? Special program? Special tool? Some kind of a measurement?

Note: Yes I tried looking for this information in the manual/online. It's not documented for some reason. And even if I find the actual answer, I'm still curious if this is a problem that can be fixed without a manual with enough perserverence. This device was manufactured between 1990 to 2000 if that helps. (maybe some options were not common at that time and I can eliminate them from my permutations)

Edit: I left out the device name on purpose to see if I could get the most general response. I'm not really THAT interested in figuring out this device, I am interested in steps to reverse engineer this in general. (So far I like the answers I'm getting - thank you!) Nevertheless this is a Liebert RAC2-8-EK auto changeover control panel. The reason I can't change the baud rate switches is because even though they are listed in the manual, I just can't see them. I see all the other switches, but not those ones. I am guessing they are "deeper in" and I don't want to take it apart just to see. Or maybe I'm just blind ... I spent one hour staring at the manual and at the board and I just can't see them. I'm sure this is a text protocol (not binary). About the echo question, it's weird because only reboot can show those white squares. Once it's booted it's hit and miss. Sometimes there is nothing echoed. (Right now it's connected to live equipment so I can't keep rebooting it, but I will take it out of operation next week so I hope to be able to reboot it many times then). I do not have a logic analyzer or oscilloscope. All I have is USB->Serial adapter

I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to)

What's the most efficient method (other than brute force) to try all the possible permutations of:

• Baud rate
• Data bits
• Stop bits
• Parity
• Flow control

What I'm really hoping is one of the following:

1. Do all settings matter? (If you can tell me that some settings are optional I don't even have to permutate those in my trial and error)
2. Do some settings give me an indication that I'm on the right track (for example I got partial output on baud rate 9600 - continuous solid white squares that looks like ascii 178 .. by the way how do I know what I'm getting in Putty other than visually trying to match it to ASCII table? Is there a better tool that displays the raw bits coming in?
3. Some other tricks that will help me figure it out (Ex. I'm using putty on windows right now, but maybe there is linux script that can connect to all different permutations one by one?)
4. Some "smell" that tells me about what to try next. Ex. Let's say I get output that scrambled in a particular way, what does that tell me that I need to try next?
5. Relationship between settings and input/output functionality. (For example, my attempt with 9600 bauds gave me that scrambled output upon hitting the enter key - but only once. After that I had to reboot the device to see that again. It's almost as though input stopped working after the first try. Does that tell me anything?)
6. Anything else that can help? Special program? Special tool? Some kind of a measurement?

Note: Yes I tried looking for this information in the manual/online. It's not documented for some reason. And even if I find the actual answer, I'm still curious if this is a problem that can be fixed without a manual with enough perserverence. This device was manufactured between 1990 to 2000 if that helps. (maybe some options were not common at that time and I can eliminate them from my permutations)

Edit: I left out the device name on purpose to see if I could get the most general response. I'm not really THAT interested in figuring out this device, I am interested in steps to reverse engineer this in general. (So far I like the answers I'm getting - thank you!) Nevertheless this is a Liebert RAC2-8-EK auto changeover control panel. Once I figure it out I will add the settings so that others don't have to fight with it. The reason I can't change the baud rate switches is because even though they are listed in the manual, I just can't see them. I see all the other switches, but not those ones. I am guessing they are "deeper in" and I don't want to take it apart just to see. Or maybe I'm just blind ... I spent one hour staring at the manual and at the board and I just can't see them. I'm sure this is a text protocol (not binary). About the echo question, it's weird because only reboot can show those white squares. Once it's booted it's hit and miss. Sometimes there is nothing echoed. (Right now it's connected to live equipment so I can't keep rebooting it, but I will take it out of operation next week so I hope to be able to reboot it many times then). I do not have a logic analyzer or oscilloscope. All I have is USB->Serial adapter

I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to)

What's the most efficient method (other than brute force) to try all the possible permutations of:

• Baud rate
• Data bits
• Stop bits
• Parity
• Flow control

What I'm really hoping is one of the following:

1. Do all settings matter? (If you can tell me that some settings are optional I don't even have to permutate those in my trial and error)
2. Do some settings give me an indication that I'm on the right track (for example I got partial output on baud rate 9600 - continuous solid white squares that looks like ascii 178 .. by the way how do I know what I'm getting in Putty other than visually trying to match it to ASCII table? Is there a better tool that displays the raw bits coming in?
3. Some other tricks that will help me figure it out (Ex. I'm using putty on windows right now, but maybe there is linux script that can connect to all different permutations one by one?)
4. Some "smell" that tells me about what to try next. Ex. Let's say I get output that scrambled in a particular way, what does that tell me that I need to try next?
5. Relationship between settings and input/output functionality. (For example, my attempt with 9600 bauds gave me that scrambled output upon hitting the enter key - but only once. After that I had to reboot the device to see that again. It's almost as though input stopped working after the first try. Does that tell me anything?)
6. Anything else that can help? Special program? Special tool? Some kind of a measurement?

Note: Yes I tried looking for this information in the manual/online. It's not documented for some reason. And even if I find the actual answer, I'm still curious if this is a problem that can be fixed without a manual with enough perserverence. This device was manufactured between 1990 to 2000 if that helps. (maybe some options were not common at that time and I can eliminate them from my permutations)

Edit: I left out the device name on purpose to see if I could get the most general response. I'm not really THAT interested in figuring out this device, I am interested in steps to reverse engineer this in general. (So far I like the answers I'm getting - thank you!) Nevertheless this is a Liebert RAC2-8-EK auto changeover control panel. The reason I can't change the baud rate switches is because even though they are listed in the manual, I just can't see them. I see all the other switches, but not those ones. I am guessing they are "deeper in" and I don't want to take it apart just to see. I'm sure this is a text protocol (not binary). About the echo question, it's weird because only reboot can show those white squares. Once it's booted it's hit and miss. Sometimes there is nothing echoed. (Right now it's connected to live equipment so I can't keep rebooting it, but I will take it out of operation next week so I hope to be able to reboot it many times then)

I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to)

What's the most efficient method (other than brute force) to try all the possible permutations of:

• Baud rate
• Data bits
• Stop bits
• Parity
• Flow control

What I'm really hoping is one of the following:

1. Do all settings matter? (If you can tell me that some settings are optional I don't even have to permutate those in my trial and error)
2. Do some settings give me an indication that I'm on the right track (for example I got partial output on baud rate 9600 - continuous solid white squares that looks like ascii 178 .. by the way how do I know what I'm getting in Putty other than visually trying to match it to ASCII table? Is there a better tool that displays the raw bits coming in?
3. Some other tricks that will help me figure it out (Ex. I'm using putty on windows right now, but maybe there is linux script that can connect to all different permutations one by one?)
4. Some "smell" that tells me about what to try next. Ex. Let's say I get output that scrambled in a particular way, what does that tell me that I need to try next?
5. Relationship between settings and input/output functionality. (For example, my attempt with 9600 bauds gave me that scrambled output upon hitting the enter key - but only once. After that I had to reboot the device to see that again. It's almost as though input stopped working after the first try. Does that tell me anything?)
6. Anything else that can help? Special program? Special tool? Some kind of a measurement?

Note: Yes I tried looking for this information in the manual/online. It's not documented for some reason. And even if I find the actual answer, I'm still curious if this is a problem that can be fixed without a manual with enough perserverence. This device was manufactured between 1990 to 2000 if that helps. (maybe some options were not common at that time and I can eliminate them from my permutations)

Edit: I left out the device name on purpose to see if I could get the most general response. I'm not really THAT interested in figuring out this device, I am interested in steps to reverse engineer this in general. (So far I like the answers I'm getting - thank you!) Nevertheless this is a Liebert RAC2-8-EK auto changeover control panel. The reason I can't change the baud rate switches is because even though they are listed in the manual, I just can't see them. I see all the other switches, but not those ones. I am guessing they are "deeper in" and I don't want to take it apart just to see. Or maybe I'm just blind ... I spent one hour staring at the manual and at the board and I just can't see them. I'm sure this is a text protocol (not binary). About the echo question, it's weird because only reboot can show those white squares. Once it's booted it's hit and miss. Sometimes there is nothing echoed. (Right now it's connected to live equipment so I can't keep rebooting it, but I will take it out of operation next week so I hope to be able to reboot it many times then). I do not have a logic analyzer or oscilloscope. All I have is USB->Serial adapter

I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to)

What's the most efficient method (other than brute force) to try all the possible permutations of:

• Baud rate
• Data bits
• Stop bits
• Parity
• Flow control

What I'm really hoping is one of the following:

1. Do all settings matter? (If you can tell me that some settings are optional I don't even have to permutate those in my trial and error)
2. Do some settings give me an indication that I'm on the right track (for example I got partial output on baud rate 9600 - continuous solid white squares that looks like ascii 178 .. by the way how do I know what I'm getting in Putty other than visually trying to match it to ASCII table? Is there a better tool that displays the raw bits coming in?
3. Some other tricks that will help me figure it out (Ex. I'm using putty on windows right now, but maybe there is linux script that can connect to all different permutations one by one?)
4. Some "smell" that tells me about what to try next. Ex. Let's say I get output that scrambled in a particular way, what does that tell me that I need to try next?
5. Relationship between settings and input/output functionality. (For example, my attempt with 9600 bauds gave me that scrambled output upon hitting the enter key - but only once. After that I had to reboot the device to see that again. It's almost as though input stopped working after the first try. Does that tell me anything?)
6. Anything else that can help? Special program? Special tool? Some kind of a measurement?

Note: Yes I tried looking for this information in the manual/online. It's not documented for some reason. And even if I find the actual answer, I'm still curious if this is a problem that can be fixed without a manual with enough perserverence. This device was manufactured between 1990 to 2000 if that helps. (maybe some options were not common at that time and I can eliminate them from my permutations)

I have an old device that I am sure works on either 1200,2400,4800 or 9600 bauds (actual setting is controlled by physical switches that I don't have access to)

What's the most efficient method (other than brute force) to try all the possible permutations of:

• Baud rate
• Data bits
• Stop bits
• Parity
• Flow control

What I'm really hoping is one of the following:

1. Do all settings matter? (If you can tell me that some settings are optional I don't even have to permutate those in my trial and error)
2. Do some settings give me an indication that I'm on the right track (for example I got partial output on baud rate 9600 - continuous solid white squares that looks like ascii 178 .. by the way how do I know what I'm getting in Putty other than visually trying to match it to ASCII table? Is there a better tool that displays the raw bits coming in?
3. Some other tricks that will help me figure it out (Ex. I'm using putty on windows right now, but maybe there is linux script that can connect to all different permutations one by one?)
4. Some "smell" that tells me about what to try next. Ex. Let's say I get output that scrambled in a particular way, what does that tell me that I need to try next?
5. Relationship between settings and input/output functionality. (For example, my attempt with 9600 bauds gave me that scrambled output upon hitting the enter key - but only once. After that I had to reboot the device to see that again. It's almost as though input stopped working after the first try. Does that tell me anything?)
6. Anything else that can help? Special program? Special tool? Some kind of a measurement?

Note: Yes I tried looking for this information in the manual/online. It's not documented for some reason. And even if I find the actual answer, I'm still curious if this is a problem that can be fixed without a manual with enough perserverence. This device was manufactured between 1990 to 2000 if that helps. (maybe some options were not common at that time and I can eliminate them from my permutations)

Edit: I left out the device name on purpose to see if I could get the most general response. I'm not really THAT interested in figuring out this device, I am interested in steps to reverse engineer this in general. (So far I like the answers I'm getting - thank you!) Nevertheless this is a Liebert RAC2-8-EK auto changeover control panel. The reason I can't change the baud rate switches is because even though they are listed in the manual, I just can't see them. I see all the other switches, but not those ones. I am guessing they are "deeper in" and I don't want to take it apart just to see. I'm sure this is a text protocol (not binary). About the echo question, it's weird because only reboot can show those white squares. Once it's booted it's hit and miss. Sometimes there is nothing echoed. (Right now it's connected to live equipment so I can't keep rebooting it, but I will take it out of operation next week so I hope to be able to reboot it many times then)