Why does Phoenix Contact use two cables for 16 channel cards?
There is a very good reason for this. Most PLC Manufacturers state a worst case scenario of having ½ of the total output channels activated (8 of 16). On a typical 16-channel output card, each channel is rated at 0.5A. If ½ the channels are on, there would be a total of 4A flowing through the I/O. Since the supply voltage and current for the card originate on the breakout module, all of the summed current must flow through the cable between the I/O card and the module. For the 16 channels of I/O, Phoenix Contact uses two 14 pin cables. Each cable contains 8 pins that are used for 8 channels of I/O and 6 pins that are used for the voltage/current supply to the card. For the positive supply, 3 pins are used and for the negative return another 3 pins are used. Per UL, a 26AWG conductor is only rated at 2A. One conductor is not enough to supply the 8 channels with the required summed current. Phoenix Contact utilizes 3 conductors per potential (+,-) to supply the voltage and current to the
