The HP 16500 is an economical way to pick up a logic analyzer. However, the 16500 is more than just a logic analyzer. Due to its modular design, it supports digital oscilloscopes, pattern generators, and high-speed logic analyzer cards. This flexible functionality and relatively low price on outlets such as eBay make them great for hobbyists and engineers. One feature that sets them apart from other units is support for remote control via X11.
This is a quick tutorial for connecting to your HP 16500B or 16500C logic analyzer over the network using X11. Lets start off with what you need:
- Network-connected Windows PC
- Network-enabled HP 16500 logic analyzer
- Enough disk space for Cygwin and the X11 package (~800MB)
Most PCs nowadays are network-enabled out of the box. However, to have both your PC and logic analyzer on a network you’ll need to have basic network equipment such as a router or switch. Chances are if you’re savvy enough to have a logic analyzer you’ll already have a basic network in place.
For the logic analyzer there are a few ways to make them network-enabled. Unfortunately, the 16500A model does not have any expansion options to permit networking. For the 16500B there are two options: the 16500H or the 16500L. Both are cards that fit in the rear of the unit and provide network connectivity. The 16500H is preferred as it provides a common RJ-45 jack of which you can plug in a standard Ethernet cable. The 16500L, on the other hand, makes use of an AUI jack to which you would need to connect a MAU which would then let you connect an Ethernet cable. If you have a 16500C you’re done as it comes with networking hardware built in.
Once you have your gear connected to a network you can begin setting up the connection. You’re going to need an X11 server and to do this we’re going to use Cygwin.
First start off downloading Cygwin at www.cygwin.com.
Once downloaded run the installer. Click next to continue.
Here select “Install from Internet”.
For this step just leave the defaults for installation directory and who to install for as shown below.
For this step, enter the location where you want to store the downloaded installation files. This can be anywhere – I usually just dump it on my desktop. Keep in mind, this location is only used to store the installation files. After the installation is finished you can delete these files.
Unless you connect to the Internet through a proxy, the default option of “Direct Connection” is sufficient for this step.
On this page select a download site. This is the site from which the installation files will be downloaded from. Try to pick one that is close to you. For instance, since I’m in Washington, I’d pick one of the the uidaho.edu servers. If in a later step problems arise while downloading the installation files, you can come back to this step and pick another site.
After a small setup is downloaded, you will see the packages available for installation.
The only change you need to make here is with the X11 package at the bottom of the list. Scroll down to it and click on the text “Default” to make it change to “Install”. Click next to proceed.
At this point the appropriate installation files will be downloaded and run. When it’s finished select where you want shortcuts to be placed. For our purposes, the desktop shortcut isn’t all that helpful. However, we definitely want the Start Menu shortcut.
Now that Cygwin and the X11 components are installed, lets move on to configuring them. First, download this file, 16500.zip. In it are two font files the 16500 logic analyzer uses. Note that if you skip this step and do not set up these font files, you can still connect to the LA and use it. However, if you click on anything that would pop up the text or number entry dialog, the LA will freeze and will require a hard reset (power cycle). Not good.
Once you’ve downloaded the zip file, navigate to the root directory where you installed Cygwin on your computer. If you used chose the default installation location, this is C:\cygwin. Then navigate usr\share\fonts\misc so that your full path is C:\cygwin\usr\share\fonts\misc.
Extract the contents of the zip file into the misc folder. In Windows XP, this is as simple as right clicking on the zip file, choosing “Extract All” and telling it to extract the files into this directory.
After the files have been extracted, fire up the X11 server by clicking Start -> Programs -> Cygwin-X -> XWin Server. This is the first thing you need to do every time you want to use the LA remotely.
A terminal window should pop up as shown below.
Now that we have the custom font files in place, we need to tell the X11 server about them. To do this, enter the command “mkfontdir /usr/share/fonts/misc/”.
For good measure, enter the command “xset fp rehash” so that the new fonts are recognized.
If no errors occur, we should now have our fonts loaded and X11 server configured. However, in order to connect we must know our PC’s IP (network) address. To do this, enter the command “ipconfig” in the X terminal. The Windows IP configuration will be displayed, including the IP address. Remember this number – it is the IP address of our X11 server.
The last thing we need to do with our X11 server is to tell it to accept connections. To do this, enter the command “xhost +”. This is the command that must be entered every time you fire up your X11 server so that the LA can connect.
With our PC setup, lets turn to the LA. Once your LA has booted up and is displaying the “home” screen select “Communications”. In the window that pops up select “Ethernet”.
Here we need to give our LA an IP address of its own. This IP address needs to be different from your PC and all other devices that might be on your network. However, it is important that the first three octets be the same as your PC’s IP address. For example, I will enter 192.168.11 since that is the first three octets of my PC’s IP address. The last octet needs to be a unique number, different from all the devices on your network. Since I don’t have a lot of devices on my network, I added a few numbers to my PC’s IP address to create the LA’s IP address.
Once entered, select “Done” to bring you back to the Communications window. Here, select “X Window”. In this window you need to enter the IP address of your PC. Leave Display and Screen at zero.
Alright, you’ve made it this far so lets see how it works! In the X Window Configuration window, select the “Disconnected” button. Yes, I know my picture only shows a “Connected” button – this is because I connected to the LA to take these screenshots, hence the Windows title bar in my pictures. Once you select the button, a window should appear on your PC showing what’s on your LA’s screen. You’ve done it! Congratulations!
If you receive a message on the LA about fonts not being loaded, something happened when you extracted the fonts (wrong directory) or told the X11 server about them. Go back and check those steps to make sure the files are in the correct directory.
When you’re done using the LA and want to power it off remember to first disconnect from the X server. You can do this the same way to connected to the server by selecting “Communications” from the home screen followed by “X Window” and finally the “Connected” button.
At this point you might be ecstatic that you can connect remotely to the LA. Before you throw a party, do note that your keyboard doesn’t have the big knob that the LA does. Don’t panic – there are keyboard shortcuts to perform the same action as the knob. When connected you can use the mouse just as you previously used your finger on the LA’s screen. The arrow keys will work to switch between various buttons. To increase or decrease a selected value, hold Shift and use the Up/Down or Left/Right arrow keys.
So there you have it. You should now be able to use your LA remotely. I find this to be a great feature as I can work on my code and use the LA from the same spot.