The generator matrix

 1  0  0  0  1  1  1
 0  1  0  0  1 (a+1)X  0
 0  0  1  0 a+1  1  0
 0  0  0  1  1  a  X
 0  0  0  0 (a+1)X  X (a+1)X

generates a code of length 7 over F4[X,sigma]/(X^2) who´s minimum homogenous weight is 8.

Homogenous weight enumerator: w(x)=1x^0+9x^8+48x^9+120x^10+972x^12+576x^13+480x^14+3840x^15+8403x^16+2592x^17+20112x^18+23040x^19+24912x^20+54336x^21+57696x^22+34560x^23+24963x^24+3888x^25+1464x^26+132x^28

The gray image is a linear code over GF(4) with n=28, k=9 and d=8.
This code was found by Heurico 1.16 in 1.73 seconds.