QTech Data Systems Q71 External 1200bps Modem - Manual (Page 3)

Q71B – Quick Start Guide – v1.1 – April 2013
www.qtech.co.nz Tel: 03 3663713
Power Supply Connections
The Q71B is designed to operate from a supply voltage in the range 8.0V DC to 15.0V DC.
A supply voltage greater than 15.0V will blow the 500mA fuse inside the Q71B.
A supply voltage less than 8.0V will result in degraded or unreliable performance.
The DATRAN XL4 RTU and the eXcel (Rev D) RTU have two RS232 ports; both can use
the Q71B for analogue radio communications.
The significant difference between the two ports, is that the lower RS232 port (RS232-B)
on the Q22D has a +Vsup DC output supply line. The Q71B can be powered via this line,
so long as jumper J23 on the Q22D is in the 1-2 position. RS232-A port on the processor
does not have this supply line, so the Q71B must be powered through the three terminal
power supply connector, the power supply connections are shown on the top cover
Left Pin
Middle Pin
Right Pin G Power Supply Negative
+ Power Supply Positive (8V – 15VDC)
Not connected
The default installation position of the Q71B is on the lower RS232 port.
All new RTUs will be configured with the correct jumper setting for this.
However, please check this jumper on existing RTUs before using a Q71B.
If using the modem on the RS232-B port do not apply power from both the
port and the external supply
If the DATRAN RTU is powered from a 24V DC system:
Do not connect the Q71Modem to this 24V DC supply.
Do not connect the Q71 modem to the RS232B port; use the 12V DC supply
that the radio uses & connect to the Q71 power connector.