Mac-based multiuser N1MM

After Operation Sizzling Pork, I thought it would be a good idea to write down how we had managed to run N1MM in multioperator mode using MacBooks at each operating position. Before those neurons completely evaporate, here’s what I remember:

1. Pull down the latest version of the documentation for N1MM. Flip to the page on “Multi-User Support”. Most of the instructions are the same whether you’re on a PC or a Mac emulating a PC. I’ll only point out the big steps and those that are Mac-specific.

2. Set up the network so all the machines can ping one another (using the OS X terminal).  That is, they should all be on the same LAN and local software firewalls should at least allow responses to pings (ICMP). In our case, the house was connected to cable-provided internet via a Linksys wireless router. From past experience, N1MM does not do well with wireless internet — it uses UDP packets, and perhaps isn’t very tolerant when some drop out due to RF interference. We went with a wired connection to each computer. In fact, in our case, we ran one wire from the router to a dumb hub, and thence to each computer. The topology doesn’t really matter, just as long as there’s no switch between the computers. We went with static ip addresses, avoiding the address range that had already been assigned by DHCP to other computers in the house. For instance, the router, 192.168.1.1 and the bedroom computer addresses 192.168.1.100 were avoided. Looking at the router set up, we also avoided 192.168.1.100 to 192.168.1.150, as this address range was assignable. We decided to designate our logging stations at 192.168.1.200, 192.168.1.201, and 192.168.1.202.

screen shot of the configuration screen for Parallels 5
Configuring Parallels 5.0

3. Fire up Parallels on each machine. If you have more than one VM defined, select one of the Windows images. Now, click “Configuration”, which should bring up the configuration editor. Click “network adapter”, and then select “Shared Networking” (rather than bridged). After clicking “OK”, hit the green arrow to boot the VM. When it comes up, it will share the same IP address as its host Mac. Next, set up the network configuration for the virtual PC using the same parameters as the Mac. So, for us, we went into TCP/IP properties and set the gateway and DNS to the router’s address (192.168.1.1), and then gave each PC it’s static IP (e.g., 192.168.1.200).

4. Set up the individual virtual computers — as usual, before the contest, download the latest update for N1MM and data files (wl_city.dta and master.dta).

5. Make sure the computers and their respective rigs work right in single user mode. Any port that controls the rig or does something else useful should be enabled as part of Parallels configuration, and the virtual PC should control it.

6. Make a list of operating station number (beginning with zero), the station label, and the static IP address. Use these numbers and names to fill out the table under >config > edit station names. Type them exactly the same on each workstation.

7. Create a new database (*.mdb) on the master station (station zero). Make sure that the entry category is compatible with multiple operating positions. If you put in “single radio”, the other workstations will be locked out while you transmit. Put in all the set-up info for the contest (Name, address, station category, power, grid square, etc.). Close N1mm on the master computer and copy the database file  to the other computers. I suggest using a USB thumb drive.

8.  Bring the computers into multimode operation (>config >multi-user mode). From this point, avoid taking the stations out of multiuser (i.e., don’t uncheck this).

The rest is pretty much the same as with a regular PC. So aside from the steps involving configuration of parallels, using a Mac with N1MM isn’t all that complicated. It could be that slower machines would have problems due to overhead, but our laptops ran WinXP without breaking a sweat. More complicated interfacing could also raise the bar, but as long the connections pass through to the virtual machine, it should be okay. I would note that in our case, we had no problem mixing a PC laptop with a couple Macs, and that the Macs in question had different versions of OS X (Leopard and Snow Leopard), and of Parallels (5.0 and 6.0), none of which seemed to matter.

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.