User`s guide

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This is the type of serial interface used on a UPB serial PIM (WMT SPIM-01) and many other

automation interface devices. In this case, the unit is expecting to talk to a PC (which has the

DTE interface).

Also notice that the DTE interface has its Receive interface on pin 2 while the DCE interface

has it’s transmit interface on pin 2. That means that in order for a DTE interface to talk to a

DCE interface, the cable needs to be straight through, not reversed on pins 2 & 3. The DTE

transmit needs to talk to the DCE receive and the DCE transmit needs to connect to the DTE

receive.

The DB9 connector pinouts are shown as follows (pins 1, & 6 – 9 are not used):

2 3 4

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