Here is what I did
1. I added the following grub.cfg

menuentry "VxWorks Test"{
set root=(hd0,msdos1)
multiboot (hd0,msdos1)/boot/vxworks_Test sysbootline:fs(0,0)host:/ata0:1/vxWorks
e=192.168.1.66 o=gei0 tn=ipc277
module /boot/vxworks_Test vxworks_Test
}

2. update-grub
3. kept vxWorks_image file at /boot/..

But i get 2 errors
error:premature end of file (hd0,msdos1)/boot/vxworks_Test
error: you need to load the kernel first.

Can somebody explain what am I missing,
I built the image using PROFILE_BOOTAPP

--- SoupGate-Win32 v1.05
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