B&B Electronics 232CL9R - Manual - Manual (Page 2)

2 232CL9R0812
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
The Model 232CL9R is a passive 9 pin RS-232 to current loop converter.
This converter requires a 12VDC-power supply at 100mA. Additional
resistors are supply for an active source.
To connect the converter to an existing current loop port, you must first
determine if the port is active or passive. For a port to be active, it must
have an internal power supply which provides the 20mA current for the
transmitter, receiver, or for both. This information should be available in
the instruction manual. If the instruction manual is not available the
simplest way to determine this is to break the loop (disconnect it) and see
if there is any DC voltage across the output or input pairs.
Current loop interfaces normally consist of four wires. They are usually
labeled T+, T-, R+, and R-. T+ and T- are the transmit plus and transmit
minus lines and data is output from that device on those lines. The R+
and R- lines are the receive plus and receive minus lines and data is input
into that device on these lines.
Interconnection of the two current loop devices is different depending on
whether your unit is active or passive. Connection to an active current
loop port is very simple. Your unit’s T+ and T- lines go to the B&B unit’s
R+ and R- lines, and your unit’s R+ and R- lines go to the B&B unit’s T+
and T- lines, as shown in figure 2.