RS232 Control of Pre/Pro

[Fargo]

Background:
I have a preamp/processor (Krell HTS 7.1) with an RS232 external control communication port. I also have an Escient DVDM-300 media manger connected to a couple of Sony DVP-CX777ES changers. The Escient media manager is connected to my home network and has a cool web interface (Fireball-PC), which I can use to control the media manager and the changer functions through PC’s connected to my network.

When I listen to music outside on the deck, I take my wireless laptop and I am able to select the music that I want to listen to and control the changers. My deck speakers are a separate zone and connected to a 2-channel amp that is connected to Zone 2 out of the pre/pro.

Problem:
I can’t control the volume.

The Fireball-PC web interface software has provisions for volume control through an external control device. The software communicates over the home network to a TCP/IP network device and you can configure the volume up/down/mute buttons with the RS232 command specific to the device you are trying to control.

Question:
Has anyone used a 10/100 mbps UTP Ethernet to serial RS232 server as the external control?

Essentially this is a device that has a DB-9 RS232 connector (connect to pre/pro RS232 com port) and an RJ-45 connector to plug in to the LAN wireless router.

Does anyone have any other suggestions to solve this problem? Comments and suggestions would be greatly appreciated.

 

[MDS]

I have a preamp/processor (Krell HTS 7.1) with an RS232 external control communication port. I also have an Escient DVDM-300 media manger connected to a couple of Sony DVP-CX777ES changers. The Escient media manager is connected to my home network and has a cool web interface (Fireball-PC), which I can use to control the media manager and the changer functions through PC’s connected to my network.

When I listen to music outside on the deck, I take my wireless laptop and I am able to select the music that I want to listen to and control the changers. My deck speakers are a separate zone and connected to a 2-channel amp that is connected to Zone 2 out of the pre/pro.

So the Fireball is on the network and you can communicate with it via a web interface from any PC connected to the network, but how are the changers connected to the Fireball? Does the Fireball also have RS232 outputs and that is how it is connected to the cd changers?

If so (or even if it is connected via some other means like USB, Firewire, null modem cable, etc) what the Fireball does is take the data sent over the network (it is acting as a 'server') and transcodes it to the specific command that the connected devices needs to see. So if for example, you click on a button that says 'next track', the Fireball sees the 'next track' command, determines that the connected device uses 100 to mean 'next track', and sends 100 over the RS232 to the changer. [Remote control commands are nothing but numbers].

Problem:
I can’t control the volume.

The Fireball-PC web interface software has provisions for volume control through an external control device. The software communicates over the home network to a TCP/IP network device and you can configure the volume up/down/mute buttons with the RS232 command specific to the device you are trying to control.

Has anyone used a 10/100 mbps UTP Ethernet to serial RS232 server as the external control?

Essentially this is a device that has a DB-9 RS232 connector (connect to pre/pro RS232 com port) and an RJ-45 connector to plug in to the LAN wireless router.

There is no such thing that I know of and probably for a good reason: how would it work? RS232 is an extremely low level serial communication protocol and the device would have to know what the payload of the IP packets contain, extract that data, and form a new stream to send out over the RS232 port (just like the Fireball itself does for the CD changers).

Is there more than one RS232 output on the Fireball so you could connect the pre/pro in addition to the changers? That should work as long as you can tell the Fireball what command to send to the pre/pro when you send the volume up/down/mute from the web interface.

If you can elaborate a bit on how everything is currently connected, we could probably come up with a workaround but it will be a hack no matter what.

Of course the simple solution is to just get an RF remote and program it with the Fireball's commands and the volume/mute functions of the pre/pro and not use the web interface.

 

[BMXTRIX]

While you can use a serial device server to accomplish certain goals, I have not done this myself and I think your biggest potential headache is that with volume control in an IP based system you may have lag time between issuing a command and the command starting - or more importantly with volume - the command ending.

You may be a bit better off going with an RF device such as a URC MX-850 remote control (or similar) with an RF base station in my opinion.

 

[Ohmen]

I use a rj45 to serial device to control my AV receiver. The commands are all executed in a timely fashion. The device I use is called a net232. Here's a link. http://gridconnect.com/net232.html
The interface works perfectly for me.

 

[AVRat]

Is the zone 2 volume level set at "fixed" or "variable" in the pre-amp? If it's fixed, you can't control the volume on the fly. It should be set at variable for that capability. See manual pg. 57.

 

[agabriel]

So it works with there application and you want to control it with another RS232 app? I have had similar problems when writing apps for certain devices, I have used a serial port monitor in the past to get around it. The one I use is available here: http://www.aggsoft.com/

I know they have a demo that might help you get the command set you need.

If your question is can you make a device that will go from ethernet to RS232 the answer is also yes, we typically use Rabbit Semiconductor products to do it. There equipment isn't terribly expensive and performs well.

Anthony

 

[MDS]

You could use a serial port monitor to discover what commands are sent to the pre/pro if you had another device that generated them but how is that going to help with communicating from the Fireball to the pre/pro?

The Fireball has its own data format that is sent using TCP/IP over Ethernet, right? If you use an ethernet to RS232 device you'd be sending the data from the Fireball's web application to the pre/pro and it won't understand it. It would be the equivalent of sending SMTP data to a web server - they both arrive via TCP/IP but the web server only understands HTTP.

You would need code that understands the data format from the web application and could translate that command to the command the pre/pro needs to see. You'd effectively have to write your own application and have it running on a PC that was connected via RS232 to the pre/pro - assuming Escient would make the details of their protocol and data format publicly available.

 

[Ohmen]

If you could configure your application to output the commands via rs-232 than the device I listed above would work. It uses software that intercepts serial data transmissions,repackages and reroutes to tcp/ip. Than the device is connected to the serial port on the pre would convert it back to serial data.

 

[Fargo]

A lot of good discussion so far but I need to provide some clarification to some of the replies.

1. I have the table of RS-232 codes supplied by Krell for use with the HTS 7.1 pre/pro RS-232 communication port.
2. The RS-232 commands will be issued from software (Fireball PC software Escient) on my PC communicating to a TCP/IP network device.
3. The Fireball PC software provided by Escient is designed to issue commands to other HT control systems like Crestron or AMX. These would be overkill for what I am trying to accomplish
4. This TCP/IP network device (the Ethernet-Serial converter I am trying to define) would be connected to my network and the RS-232 communication port on the pre/pro.
5. This TCP/IP device will have a network address so that I can communicate to it from my PC. The commands for controlling the pre/pro volume do not go through the Escient DVDM-300.
6. The Krell HTS 7.1 Zone-2 volume can be configured to be either fixed or variable. This is configurable through the user setup menu.

Ohmen, thanks! I checked out the link you supplied. This is what I was looking for and I believe that it will accomplish the control I am looking for. Thanks all for your input I let you know how it works out.

 

[MDS]

5. This TCP/IP device will have a network address so that I can communicate to it from my PC. The commands for controlling the pre/pro volume do not go through the Escient DVDM-300.

Had you said that early on I wouldn't have misinterpreted how the system works and gone into my long diatribe about how you can't just connect an ethernet->RS232 device.

The device Ohmen linked should work just fine then if the code is running on your PC and can communicate directly with it instead of sending the commands to the Fireball...and you won't need a serial monitor to reverse engineer the Krell pre/pro command set because they were kind enough to supply them.

It sounds like a pretty cool setup.

 

[agabriel]

So are you looking to make you own device that converts ethernet to RS232 or buy a commercial one?

 

[Fargo]

Purchase as opposed to build. It appears that a retail component is available fro about $100.