How do I connect a Shure DFR11EQ or DP11EQ to a 3 wire or 5 wire control system?
The DFR11EQ uses a standard 7 wire RS-232 port for control. It is possible to control the DFR11EQ with a control system that provides a 5 or 7 wire RS-232 output.
Seven wire operation
Connect the RX, TX, DTR, GND, DSR, RTS, and CTS conductors to the appropriate terminals on the control device.
Five wire operation
Using the RS-232 wiring diagram in the DFR11EQ owner’s manual, connect the RX, TX, GND, RTS, and CTS to the five wire RS-232 port on the control unit. This would be similar to the RS-232 port number 4 on the AMX Axcent2 system. The DFR11EQ requires a voltage of 5 to 12 volts on the DTR line. This voltage tells the microprocessor to accept any data that it receives on the TX line. This voltage can be supplied by any of the 12 VDC outputs from the AMX. See the following diagram.
The resistor is placed in-line to limit the current going to the DTR of the DFR11EQ.
Three wire operation
When using three wire operation the hardware hand-shaking capabilities of RS232 are disabled. To make the DFR11EQ handle the messages without hand-shaking, all messages sent from the AMX must be delayed. Also, when using three wire configuration, the DTR line, as well as the CTS line, must still be supplied a DC voltage as shown above in the five wire operation. This wiring scheme is not recommended. It is better to use 7 wire or 5 wire RS-232.