Cannot make program start with systemd

Question

Hello there,
as a newby i am slowly getting to grips with Arch Linux, but I cannot resolve the following after trying for some time.
I have ArchLinux running on a Raspberry PI.
I have a programme called aprx installed and to run it, I execute /sbin/aprx. The programme then starts, creates a pid file, called aprx.pid in the var/run directory and works smoothly, The programme uses a usn to serial port, which also works fine.(ttyUSB0)
Now I need this program to start at boot time, so I read up on systemd, and I wrote a file called aprx.service, put it in /etc/systemd/systems/, did all the right things to enable it as a service, i believe...
The content of aprx.service is as follows:
Unit]
Description=APRX Server, an iGate and Digipeater
After=dev-ttyUSB0.device
[Service]
ExecStart=/sbin/aprx
[Install]
WantedBy=multi-user.target
After reboot I get the following output on systemctl - status aprx.service
[root@pa0esh ~]# systemctl status aprx.service
aprx.service - APRX Server, an iGate and Digipeater
      Loaded: loaded (/etc/systemd/system/aprx.service; enabled)
      Active: inactive (dead) since Thu, 1970-01-01 01:00:06 BST; 43 years and 0 months ago
     Process: 97 ExecStart=/sbin/aprx (code=exited, status=0/SUCCESS)
      CGroup: name=systemd:/system/aprx.service
[root@pa0esh ~]#
However, the programme did nit really start, and there is also not a pid file.
So what am I doing wrong here ?
Any help is much appreciated.
Erik

Answer 1

Yes indeed, it is  ArchARM, Trilby
And so i found the solution for the service file aprx.service
Still, thanks a lot for pointing me out.
Erik
[Unit]
Description=APRX Server, an iGate and Digipeater
After=dev-ttyUSB0.device
[Service]
User=root
Type=oneshot
RemainAfterExit=yes
ExecStart=/sbin/aprx
[Install]
WantedBy=multi-user.target