Shaqada ugu weyn ee beddelaha 485 waa inuu u beddelo calaamadda RS-232 ee hal-dhammaad ah oo loo beddelo calaamad RS-485 ama RS-422 ah oo dheellitiran. Sababo la xiriira gudbinta macluumaadka fog-fog iyo awood xoog leh oo ka-hortagga faragelinta, beddelayaasha rs485 ayaa si weyn loogu isticmaalaa isgaarsiinta amniga iyo qaybaha kale. Si kastaba ha ahaatee, isticmaalayaashu waxay inta badan la kulmaan faragelinta calaamadaha. Haddaba, maxaa sababa in calaamadda beddelaha rs485 la farageliyo?

1. Faragelinta iswaafajinta, taas oo inta badan ka timaada isbarbardhiga culeyska nidaamka aan macquul ahayn. Tusaale ahaan, xariiqda calaamaduhu aad bay u dheer tahay, aad u badan (masaafada dheer) ee fiilooyinka xiddigaha, culeys aad u badan, ma jiro nidaam u dhigma iska caabin, iwm, taas oo keenta in nidaamku si fiican u shaqeeyo oo uu ku guuldareysto inuu si deggan u shaqeeyo.

2. Faragelinta qaabka caadiga ah ee xooggan. Xaaladdan waxaa badanaa keena si toos ah ama si aan toos ahayn ee qalabka helitaanka meelo kala duwan, taas oo keenta xidhiidhka ka dhexeeya khadka signalka iyo "dhulka qalabka" ama "dhulka qalabka" (sida caadiga ah 50 Hz) oo ay keento calaamad xad-dhaaf ah. Soo dhawaynta wax qabadku mararka qaarkood way maqan tahay, ama xitaa lama aqbali karo mar kasta. Intaa waxaa dheer, soo dhaweynta xogta lama xaqiijin karo haddii masaafada u dhaxaysa helitaanka iyo dirista ay tahay hal mitir.

3. Qalab-la'aanta qalabka, sida caadiga ah sababtoo ah waxaa jira taariikh koronto sare leh oo khadka ah (joojinta hillaaca, daadinta), taasoo keenaysa dhibaatooyin rs485 qalabka beddelka qalabka shakhsi ahaaneed ee nidaamka, oo saameeya soo dhaweynta guud.

4. Khaladaadka khadka, sida wareegga gaaban ee maxaliga ah ama wareegga jaban ee xariiqda calaamadda, waxay inta badan ka dhigaan nidaamka inuu u shaqeeyo gudaha ama si caadi ah u shaqeeyo, laakiin shaqadu waa mid aan degganayn.