ComBricks SALT and Pepper Kit

The ComBricks PROFIBUS DP SALT and Pepper Kit makes it possible to use non-standard PROFIBUS cable in a PROFIBUS DP segment. This is the only product on the market that enables the use of a cable other than standard PROFIBUS cable. By adjusting the terminating resistors, the SALT & Pepper kit lets you use any cable with 2 wires (A & B). Only have twisted pair buried in that conduit? Will it take hours of effort to remove that old DeviceNet cable? No problem! By using this kit it is now possible to use those cables reliably in your installation.

This kit works by modifying the terminating resistor values to match the impedance of the alternate cable. This calculation is easily done by using the provided software tool. Just enter the cable’s impedance and the tool will give you values to use on the rotary switches located on the ComBricks SALT module and the T1-Pepper active terminator. Since the SALT module has a built-in oscilloscope, ProfiTrace OE can be used to check the signals of the segment to make sure they look like good PROFIBUS messages. All you have to do is bring up ProfiTrace OE in your web-browser and check!

The SALT (Scope ALTernate Cable) Module in this Kit must be used as a repeater to tie into the rest of the installation. It creates a new segment with the non-standard cable run. The rest of the PROFIBUS DP network is connected to the 1-Channel DP Module that is included in the kit.

The SALT and Pepper kit is also useful for installations that have standard PROFIBUS Cable, but have problems due to EMF (Electro-Magnetic-Field) interference from nearby power lines. The trick in this case is to use the kit to raise the “idle line” (or bias voltage) which is the voltage present on the bus between messages. EMF often shows up on this idle line, and if it is severe, the disturbance can cause parts of the idle line to cross the forbidden “zero volt” line. By using the SALT & Pepper kit, the idle line can be moved up, thus giving you a ‘raised floor” to allow the EMF disturbance and still run smoothly. This can be a valuable capability when the cost of re-routing power cables is considered.

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