7I90HD 16
OPERATION
PC HOST ADAPTER
In order to run any of the serial command line utilities a RS-422 adapter is needed.
Mesa can provide a suitable adapter. Two such adapters are 3I21 or 3I22. These adapters
connects the RJ-45 RS-422 interface on the 7I90HD to a DB9 serial port (3I21) or USB
port (3I22) and provide 5V link power.
MINIMAL HOST PC ADAPTER
A simple home made host adapter can be made by directly connecting RS-232
signals from a 9 pin PC serial port or USB RS-232 adapter to the 7I90HD’s RS-422
signals via a one ended CAT5 cable. A single resistor between RS-232 TXD and RS-422
RXB is needed to prevent overloading the RS-232 TXD output
CAT5 PIN
DE-9F PIN
CAT5 SIGNAL
DE-9F SIGNAL
CAT5 COLOR
1
5
RXA
GND
ORANGE WHITE
2
3
RXB (1)
TXD (1)
ORANGE
3
XX
TXA
XX
GREEN WHITE
4
5
GND
GND
BLUE
5
5
GND
GND
BLUE WHITE
6
2
TXB
RXD
GREEN
7
XX
+5V (2)
XX
BROWN WHITE
8
XX
+5V (2)
XX
BROWN
Notes:
1. Connect via 470 Ohm 1/4 watt resistor. All other signals directly connected
2. If not supplied by the adapter, +5V power must be supplied via the 7I90HDs 5V power
connector P7