Tracer AV
10
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2.3.3 Serial Communications
The pinned DB-9 connector marked as COMM is connected to EDP port J3. It is bi-directional communication to be used for a
PC connection.
There are two socketed DB-9 connectors for remote displays which are connected to the serial port J4. The remote display’s
DC power and communications are run in the same three-conductor cable. The serial port data is transmitted on the 20 mA pins
to the remote displays.
2.3.4 Digital I/O
Digital inputs can be set to provide several indicator functions, including all keypad functions. In the Tracer AV, these inputs are
set to
Zero
and
Units
for the remote keypad. The inputs are active (on) with low voltage (0 VDC) and can be driven by TTL or 5V
logic without additional hardware. LEDs on the CPU board light when digital inputs are active.
Digital outputs are typically used to control relays that drive other equipment. In the Tracer AV, the setpoint value will cause the
display to flash. Outputs are designed to sink not source, switching current. Each output is a normally open connector circuit,
capable of sinking 250 mA when active. Digital outputs are wired to switch relays when the digital output is active (low, 0 VDC)
with reference to 5 VDC supply. LEDs on the CPU board light when the digital outputs are active.
DB-9
EDP Port
COMM
J3
Function
Pad
Pin 2
1
EDP TxD
P 1
Pin 3
2
EDP RxD
P 2
Pin 5
3
EDP Gnd
P 3
Table 2-2. EDP Port/COM
DB-9
Serial Port Digital Output
Remote
J4
J6
Function
Pad
n/a
--
4
+5 VDC
P 4
n/a
4
--
20 mA+
P 5
n/a
5
--
20 mA-
P 6
Pin 1
--
--
+7.5 VDC
n/a
Pin 2
--
--
Gnd
n/a
Pin 9
--
--
TxD
n/a
Table 2-3. Serial Port/Remote Display
DB-9
Digital Input
J2
J12
Function
Pad Number
Pin 4
--
1
Setup
P 10
Pin 5
3
--
Gnd
P 7
Pin 8
1
--
Dig In 1
P 9
Pin 9
2
--
Dig In 2
P 8
Table 2-4. Digital Input/Remote Keypad
Port
Connector
Pin
Function
Digital Output
J6
1
Gnd
2
DO 1
3
DO 2
4
+5V
Table 2-5. J6 Digital Outputs
