7I44 6
OPERATION
5V POWER
The 7I44 requires ~100 mA of 5V power for operation. This power will increase
based onthe number of terminated TXoutputs used, and powerused byexternal devices.
If only lowpower external devices are used the 7I44 can be run entirely from cable
power. (W1 UP) If more than about 400mA of total external power is used. It is suggested
that the 7I44 be powered form an external 5V source (W1 DOWN)
RS-485 CAPABLE CHANNELS
All of the serial channels on the 7I44 have output enables and can be used for RS-
485 half duplex type applications. For 2 wire half duplex type RS-485 interfaces, the RX+
and TX+ lines and the RX- and TX- lines should be tied together at the 7I44.
INTERFACING WITH MESA SERIAL DEVICES
The 7I44 in intended as an interface to MESA’s serial I/O devices that use RS-422
communication and RJ45/CAT5 cable for the serial interface. These devices include the
7I64 Isolated I/O interface, the 8I20 3phase drive, the 7I66 isolated I/O interface, the 7I69
TTL I/O interface, 7I70 isolated input, 7I71 isolatedoutput, and the7I73 pendant interface.
Straight through CAT5 or CAT6 cables canbe used but CAT6 is recommended for
better signal fidelity and lower voltage drop. Make sure you are using straight through
cables. Random cables from routers etc are likely to be crossover cables which will not
work and may even damage the 7I44/remote device.
