J2 485 System Manual
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Contents
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J2 485 System ManualVersion 1.0 May 19, 201219Serial portsThe J2 485 has five external RS232 serial ports, all of which can be powered. The serialports are standard RS-232 ports with a DB9 male connector. I in a normal configuration,serial ports are mapped to COM 1-5.There also four internal serial ports, one of which is used for the resistive touch controllerand the others are reserved for other internal options.COM ports 1-5 can supply power to an external device when required, like the optionalJ2 Customer Display. COM 1 can supply +5 volt and COM 2-5 supply +12 volts. Thevoltage is supplied on pin 9 (RI) of the DB9 connector. The maximum current is 1000maand is over-current protected. A BIOS setting is used to enable the voltage on each port.J2 does not normally recommend using the +5 volt option on COM 1 and it is only therefor some legacy devices. The problem is that it is easy for a +5 volt device to be pluggedinto a +12 enable serial port by mistake, which will burn out the +5 volt device. A goodalternative to powering a +5 volt serial device, or any +5V device would be to use powerfrom an unused USB port. Cables for this are readily available (see below):DB9 pin out serial portsPin RS2321 DCD2 RD3 TD4 DTR5 GND6 DSR7 RTS8 CTS9 RIUSB to +5V cable |
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