422 operation, Lk6 and lk7, Should be in posit – Eurotech Appliances VIPER / VIPER-LITE PXA255 User Manual
Page 99: E network. see, Rs485/422, Configuration – lk4, lk5, lk6 and lk7, 371h, For det, Required, Rs485/422 configuration – lk4, lk5, lk6 and lk7