Virtual HP-IL example

This example shows the usage of a real HP-IL device (HP-41 equipped with HP-IL module) linked via a PIL-Box with virtual HP-IL devices connected by TCP/IP. The screen shots show first ILPer with enabled scope, then second an ILPer instance with disabled scope and third ILScope. ILScope is a separate IL protocol debugger (a sniffer) which can be placed anywhere in the loop. It is mainly ILPer without the simulation of peripherals.

Like with real devices you also have to connect the virtual devices in a loop. So instead of having an input cable, you have the "In Port" number, instead of having the output cable, you have the "Out Port" number which must be "plugged" together.

The heart of the new system is the program ILPilbox, the bridge between J-F Garnier PIL-Box hardware and the virtual HP interface loop. Meanwhile we have also two HP-IL controller programs with native support of virtual HP-IL. These are Emu71/Win emulating the HP-71B and V41 emulating the HP-41 calculator.

I also tested the setup in a LAN where one instance of ILPer was running on a different computer. For all network traffic you will have to permit the communication in your firewall. For security reasons I personally restricted the access to computers in the same subnet.

Setup the loop

As you see in the "Setup the loop" picture, every program in the loop has a unique "In Port" number. The "Out Port" number in combination with the "Out TCP/IP Address" points to the "In Port" number of the next device in the loop. The "Out Port" number of the last device in the loop then points to the "In Port" of the first device. The loop is closed. Because the next device could be on a different computer, the "Out TCP/IP Address" must be given to identify this next computer. When the next device is on the same computer use "localhost" as "Out TCP/IP Address" else the computer name or TCP/IP address of the computer with the device next in the loop.

The working loop

(c) Christoph Gießelink, March 2024