Wednesday, August 27, 2014

Choosing the right PROFIBUS cable

Choosing the right PROFIBUS cable
Is the application PROFIBUS DP or PROFIBUS PA?
My cable is purple, can I use it?
DP cable has a 150Ω  impedance
PA cable has a 100Ω  impedance
RS485, CAN bus, DeviceNet and other data cables can be purple in colour but have a 120 Ω impedance
So what if my cable impedance is wrong?
PROFIBUS devices and their terminations are designed to match specific impedance.  Your data signal will degrade and your waveforms will be malformed.
Use a test tool like PROFIBUS Troubleshooting Toolkit from PROCENTEC with built in scope function to check your signals

The T1 Pepper Active Terminator matches can sort our any impedance mismatches

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