Front Panel Operation
2-121
The Model 6517A’s Digital I/O port can be used to control
external circuitry. The port provides four output lines and
one input line (input line is for calibration use only — refer
to the Model 6517 Service Manual). Each open-collector
output can be set high (+5V) or low (0V) and will sink up to
100mA. The four output lines can also operate external sup-
plies from +5V to +30V.
Use the DIGITAL I/O Menu to select the following options:
• STATE
ON or OFF selectable for each output line (1 through
4). Use to check or change the output state.
• LOGIC-SENSE
ACTIVE-HIGH or ACTIVE-LOW selectable for each
output line (TTL1 through TTL4). Use to check or
change the output sense.
Controlling digital circuitry
Each of the four digital, open-collector outputs (connector
J1015, pins 4 through 7) includes a built-in pull up resistor to
+5V. The output transistor is capable of sinking up to 100mA
from voltages up to +30V. The outputs can be controlled in-
dependently or tied to one of four limit values (two high, two
low). Paragraph 2.19.5 contains information on controlling
digital outputs from the limits menu.
External voltage supply
Each output can be operated from external voltage supplies
(voltage range from +5V to +30V applied through the exter-
nal device being driven). Refer to Figure 2-80 for a simplified
schematic of the digital I/O. The high current sink capacity of
the output driver allows direct control of relays, solenoids,
and lamps (no additional circuitry needed). Each output
channel contains a fly-back diode for protection when
switching inductive loads (such as a low power solenoid or
relay coils). To use these fly-back diodes, connect the exter-
nal supply voltage to pin 3 of J1015 (the digital I/O port).
Make sure the external supply voltage is b5V and
+30V and the current required by the device does not exceed
100mA.
CAUTION
Do not apply more than 100mA maxi-
mum current or 30V maximum
voltage on pin 3 of J1015 (the digital I/O
port). Applying current or voltage ex-
ceeding these limits may damage the in-
strument.
Pin 5 - Digital Output #2
Pin 6 - Digital Output #3
Pin 7 - Digital Output #4
10
Ω
Pin 3 - External Voltage Flyback
Connection (+5V to +30V)
+5V
10k
Ω
Pin 4 -Digital Output #1
Pin 8 -Digital Ground
Digital Output
Flyback Diodes
1
2
3
4
5
6
7
8
DIGITAL
OUT
(Connector J1015)
Pin 1 - +5VDC
+5V
510
Ω
Figure 2-80
Digital I/O port simplified schematic
Shown for Digital Output #1; Digital Outputs #2, #3, & #4 are similar
Содержание 6517A
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