7I47S 8
OPERATION
5V POWER
The 7I47S requires ~100 mA of 5V power for operation. This power will increase
based on the number of terminated TX outputs used, up to a maximum of ~400 mA.
Power for the 7I47S logic is normally supplied from pin 49 of the 50 conductor
controller cable. P1 supplies power only to the 5V I/O terminals on P3 and P4 (chiefly for
encoder power).
If W1 is on the left hand position, the controller cable will supply both the logic and
I/O power and P1 can remain unconnected. This mode can be used for testing but it is
suggested that W1 be placed in the right hand position and I/O power be supplied via P1
for most applications.
The power from connector P1 Passes through a 1.3A PTC device before being
routed to the I/O terminals. This limits the total I/O power supplied by the 7I47S to ~800
mA in 0 to 70C ambients.
RS-422 OUTPUT DRIVE
The 7I47Ss outputs are designed to drive singly terminated RS-422 lines or remote
opto-isolator diodes. Maximum output drive is 35 mA. The 7I47S outputs can be used
individually for interfacing single ended loads. Unloaded outputs swing to 5V (Full 5V
CMOS outputs)
INPUT/OUTPUT POLARITY
The RS-422 differential I/O signals consists of a inverted and non-inverted signal
pair for each unbalanced signal on the Anything I/O side of the interface. The TX(N) and
RX(N) signals are the inverted signals. The /TX(N) and /RX(N) signals are the non-
inverted RS-422 signals. This seemingly inverted convention is used to maintain
compatibility with encoder inputs on other Mesa products and RS-422 serial usage. For
driving single ended loads, either the inverting or non-inverting output may be chosen.
MONITOR / ENCODER LEDS
Monitor LEDs are provided on the RX(N) lines, especially for use with encoder
inputs. These LEDs are arranged in 4 groups of 3 to monitor the A/B/INDEX lines of 4
encoders.
