Frequently Asked Questions
This FAQ applies to Heyu Version 2.
Last updated 08/25/2007
Q: What is Heyu?
A: Heyu is a program that allows your computer to control devices by
transmitting information over your house's power lines.
Q: What hardware is needed?
A: The X-10 CM11A power-line communications interface connects to a
serial port on your computer. It translates Heyu commands
to a signal that's transmitted over the AC wiring in your house.
A CM12U is essentially the same thing for 230 Volt systems.
X10 receiver modules (lamp, appliance, etc) listen for the signal
on the AC lines and respond appropriately.
Heyu can also receive and process X10 RF signals from a WGL
W800RF32A, an X-10 MR26A, or RFXCOM RF receiver connected to a
second serial port.
Q: Why the silly name?
A: In the words of Heyu's creator: "My kids are grown and on their own,
and I kind of missed being able to shout out "Hey You! Turn the
Q: My computer doesn't have RS232 serial ports, only USB ports. Can
I use a USB-Serial adapter?
A: Yes, provided that your OS has kernel drivers for the specific adapter.
Q: Does Heyu support the European model CM11E which has a USB plug?
A: This is the same CM11 serial interface but supplied with a USB-Serial
adapter cable. See the previous question and answer. Note however
that some Linux users have reported frequent lockups with this adapter
(and other adapters using a Prolific chipset) which ceased when the
adapter was replaced by one using a FTDI chipset.
Q: I'm using a USB-Serial adapter and when I try to send a Heyu command
from the command line I get the message "RI serial line may be stuck"
after a long delay.
A: This is a problem with some adapters using an older Prolific chip.
The workaround is to put the directive 'CHECK_RI_LINE NO' in your
Heyu configuration file.
Q: Does Heyu support the new X-10 CM15A "ActiveHome Pro" interface?
A: No. The CM15A is a USB-only device requiring a custom driver.
Q: Why do you sometimes mention "X-10" and other times "X10". What's
A: X-10 refers to the company "X-10 (USA) Inc." or one of its products.
X10 refers to the protocol for AC power-line signals or RF signals
developed by that company but also supported by products from other
Q: What OS will Heyu run on?
A: The program was developed on a Linux system. The compiled program
should work on any Linux system, although some of the directories
may differ between Slackware, Red Hat and Debian. Check the system
logs if the program does not run as expected.
The program may be portable to other Unix variants. The source code
is included on the web site. It has been reported that the program
compiles (and runs) on Linux, BSD, FreeBSD, OpenBSD, NetBSD, Mac OS X,
SunOS, Solaris and NEXTSTEP 3.3
Q: I downloaded the Heyu source file, now what?
A: The whole package is included in the file heyu-VERSION.tgz This is a
tar file that has been gzipped. Some of the individual parts are
also available from the web site.
The tar file will unpack into subdirectory ./heyu-VERSION/
CD to the directory of your choice. Copy the tarred file there and type:
gunzip -c heyu-VERSION.tgz | tar xvf -
To compile the program, run the Configure program (./Configure) as an
ordinary user and then type 'make'. The resulting executable program
is named simply 'heyu'.
To install the program and man pages, type 'make install' while logged
in as root. It will try to locate your existing configuration file
(if any) or will otherwise offer to install a default configuration
file if appropriate.
If necessary, you can copy an existing configuration file to Heyu's base
directory and edit it to suit your environment.
Q: What is meant by "Heyu's base directory"?
A: The base directory is where the configuration file is stored and where
Heyu will read and write certain other files. Heyu will first look
for the file .heyu/x10config under the user's home directory. If not
found there it will look for /etc/heyu/x10.conf (under Linux - the
location may vary for other operating systems).
Q: What is the x10config (or x10.conf) file?
A: The x10config file is the configuration file used to set various
definitions and options for Heyu, for example the serial port to
which the CM11A is connected.
X10 devices are normally addressed by a code represented by a letter
and a number. The x10config file provides a way to associate 'names'
(aliases) with devices. For example, the name "lamp" can be used
instead of D4, or "porch-light" could be used instead of device K15.
The x10config file also provides the means for the user to control
many details about the way Heyu operates. See the man page
Q: What's the heyu_relay process that's always running in the background?
A: This is the process that gathers the output from the CM11 and stores
it for any program that may need it. It also responds to the CM11's
requests for time updates and power failures.
The relay allows several programs to communicate with the CM11.
As an example, you can run the program in monitor mode in one window
to watch what's happening with the CM11, while cron's sending a
a command to the CM11 based on the system clock.
Q: How does the heyu_relay process get started?
A: The relay is automatically started the first time the program runs.
If it's killed for any reason, it will start up again the next time
the program runs.
Q: What is the Heyu State Engine?
A: This is the optional heyu_engine process which runs in the background.
It maintains a record of the state (On, Off, Dim level) of each module
as determined by sent and received X10 power line signals. It is
responsible for launching scripts or executable binaries based on X10
signals. It can also write a log file on the user's hard drive.
This process can be started manually by entering 'heyu_engine' at the
command line. If the directive "START_ENGINE AUTO" is included in the
configuration file, it will be started along with Heyu's other
background process when the command 'heyu start' is entered.
Q: What is the Heyu Auxiliary process?
A: This is a background process, heyu_aux, which will read and decode
X10 RF signals from a WGL W800RF32A or X-10 MR26A RF receiver connected
to a second serial port. The signals are either transceived directly
to the power line via the CM11A or are sent to the Heyu State Engine
for further processing, such as launching scripts. See the man page
x10aux(5) for details.
If the auxiliary serial port and RF receiver type are specified in the
configuration file with the TTY_AUX directive, this process can be
started manually by entering 'heyu aux' at the command line, or will
be started automatically along with Heyu's other background processes
when the command 'heyu start' is entered.
Q: What is the Heyu Monitor?
A: This is a process which will display sent or received X10 power line
signals in a terminal window. To start the process, open a new
terminal window and enter 'heyu monitor' at its command line.
Q: I'm running the program for the first time, and it's saying:
"Invalid status response (was 0 bytes instead of 14)" and it's
not turning anything on or off.
A: This may indicate several things.
a) The CM11 may not be connected to the correct serial port. COM1
in DOS/Windows is /dev/ttyS0 in Linux.
b) The CM11 may not be plugged into the wall or the outlet may be
c) The CM11 may need to be prodded. Some CM11's go to sleep when
first plugged in. They wake up when they see the first X10 traffic
on the AC lines. Use a mini-controller or wireless transmitter
to turn an X10 module on or off.
d) You may be running another program (getty or a mouse driver) on the
Q: I have my CM11 set to house code A. Will it report X10 events for
A: Yes, any activity will be reported in both a Heyu Monitor and in the
log file written by the Heyu State Engine (if thus configured). The
'monitored devices' line of the 'heyu info' report shows the limited
information stored in the CM11A's internal registers, which is restricted
to a single housecode.
Q: Is there a web page?
A: Yes. http://www.heyu.org should bring you to the web page.
Q: I run the program and get the output:
"Unable to open file ..."
A: This generally means that the program can't open a necessary file.
Check the log files in /var/adm for error messages complaining about
files or directories. Unfortunately, not all Unix systems use the
same directories for temp files, lock files and such.
Q: I have an X-10 CP290 instead of a CM11. Will Heyu work with it?
A: No. Check the web page of Paul Fox. There's a pointer to it at the
Heyu website listed above.
Q: What version number of Heyu am I running?
A: At the command line, enter 'heyu version'.
Q: Are there other Linux programs that will run a CM11?
There is another one called x10d that uses a network driver approach,
so you set up a network service and telnet to that port to issue
commands. The author is Daniel D. Lanciani and a modified version
was posted to the net by Neil Cherry.
The web location for Dan Lanciani's x10d is http://www.danlan.com/
There's the freeBSD daemon also called x10d at
Q: I want to control other programs based on X10 signals. Can I?
A: Yes. Heyu has the capability to run shell commands and launch
scripts or executable binaries. See the man page x10scripts(5).
Q: Don't I need the Xtend program to run other programs?
A: With Heyu version 1, the auxiliary program by David Shaw named
Xtend was required, however the functionality is built into Heyu
version 2 and no auxiliary program is required.
Q: I made the required entries in the configuration file to run
a script when an X10 signal is received, but it doesn't run.
A: Whenever changes are made in the configuration file, you must
run 'heyu restart'. This will incorporate the changes in all
the Heyu background processes..
Q: My script runs when it receives the X10 signal over the power
line, but it won't run when I send the same signal from the
Heyu command line. What's wrong? I'm using the directive:
SCRIPT A1 on :: myscript.sh
A: The launch conditions for your script must specify the sources
of the signal you want to allow to execute your script in
addition to the default ("RCVI"). For signals sent from the
command line, add the source SNDC, i.e.,
SCRIPT A1 on sndc :: myscript.sh
See man page x10config(5) and x10scripts(5) for descriptions
of other sources.
Q: The heyu_relay daemon doesn't die when I do a 'heyu stop'.
A: You have to have permissions to kill(1) the daemon to stop it.
Q: The program does not work from my crontab.
A: The most likely problem is that Heyu cannot find the configuration
file. Use either Heyu's -c command line option or the X10CONFIG
environment variable to specify the full pathspec,
Q: Does Heyu do schedules, as in timers and fast macros?
A: Yes. See man page x10sched(5). By default, Heyu looks for
a file named x10.sched in the Heyu base directory. An
example file named x10.sched.sample is included in the
Heyu source tar file.
Q: Do I have to do anything special with a schedule in order to have it
executed by the CM11A?
A: Yes, you must specifically load the schedule into the CM11A memory
by entering 'heyu upload' at the command line.
Q: Does Heyu handle Leap Year properly? How about Daylight Saving Time?
A: Yes. The dates and times you program in the schedule file are
automatically adjusted by Heyu for Leap Years and Daylight Saving Time.
Q: Will my CM11A schedule stop working on New Years Day as it does
with the ActiveHome program for Windows?
A: No. Heyu has several options for working around the relatively
primative clock/calendar hardware in the CM11A.
Q: I unplugged the CM11A from the computer and my uploaded schedule
worked fine for a few days, but then it started doing crazy things.
A: When disconnecting from the computer, always unplug the serial cable at
the CM11A end. The CM11A is very susceptible to stray noise pickup
from a dangling cable which causes it to lose its settings.
Q: I just installed Heyu and only an 'info' will work (but takes about
10 seconds), all other commands fail. ActiveHome works fine on the
same machine under Win95.
A: The clue here is 'real slow'. Sometimes plug and play systems change
the interrupts on the serial ports. Sometimes you end up sharing
interrupts with another device. When that happens, you may end up having
to wait for the other device to need attention before your system will
look at the serial port.
Q: Heyu works, but it take 6 to 10 seconds to send a command.
A: See the answer to the previous question. Heyu should take about
1 second to send an on or off comamnd. The only exception is the
very first time, as it sets up the heyu_relay daemon.
Dim and bright may take a few seconds longer, but not much more than
about 4 seconds.
Q: What are some things that get in the way of Heyu communicating with the
A: There are only a few things that interfere with Heyu and the CM11.
a) A running getty against the serial port.
b) Shared interrupts on an ISA based serial port. This sometimes happens
when a Plug and Play card is reconfigured.
(COM1 and 3 or 2 and 4 are frequently shared under DOS and Windows.)
c) A powerline signal coming in while the computer is sending a command.
Q: I use OpenBSD and don't see any information from the CM11.
Running 'heyu info' says Firmware revision Level = 0 and Interface clock
not yet set.
A: OpenBSD requires that you add the following to /etc/ttys:
tty00 "/usr/libexec/getty std.9600" unknown off local
See also the OpenBSD FAQ on the Heyu web page.
Q: I made a local modification to Heyu. How do I build the program?
A: First, stop the running version of the program with 'heyu stop'.
A makefile is included that will create the program. Just type the
command 'make' in the directory where you unpacked the source.
When satisfied with the modifications, type 'make install' while
logged in as root.
Q: I don't need the Heyu program anymore. I like Windows better. How
do I get rid of it?
A: There is an uninstall option built into the Makefile. Cd to the
source directory for Heyu and, as root, type 'make uninstall'.
Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Daniel B. Suthers,
Pleasanton Ca, 94588 USA. E-mail: dbs -at- tanj.com
Updated for Heyu version 2 by Charles W. Sullivan.