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Quick Talk Features/ Applications Manual
Page 14
16.
MONITORING 4 - 20 mA
SENSOR CURRENT LOOPS
W/ ANALOG MODES
TO USE QUICK TALK TO MONITOR 4-20 mA SENSOR
CURRENT LOOPS WITH ANALOG INPUT MODES
Quick Talk can act as a current sink after a resistor is
connected between the Switch 1 positive and negative
terminals. The resistance value is selected to scale the
current to the permitted 0 - 5 Voltage range for the Switch 1
input to Quick Talk. See the following formula, and Fig–5.
5 Volts (max. permitted Voltage)
---------------------------------------------------------
20 mA (max. current from sensor loop)
NOTES: Using a lower resistance value with the 4-20 mA
current loop produces less than 5 V at the Switch
1 input; since the full 5 Volt range is not used,
measurement resolution is reduced.
Using a higher resistance value at 20 mA
produces greater than 5V at the Switch 1 input,
which risks damaging the Quick Talk unit.
4-20mA Current Loop Input
EXT. PWR.
FIG–5.
(EXAMPLE CONNECTION DIAGRAM)
18.
USING LATCHING OPTION
TO USE LATCHING MODE:
Use the Quick Talk latching mode application if repeated
transmissions are desired with a momentary switch
(i.e.: a push-button). The latching effect maintains message
repeats after the momentary switch change has ended.
EXAMPLE: To use a Quick Talk in a paint department, set
it to repeat phrase transmissions after the
"Press for Help" push-button is activated. In this
example, the recorded phrase transmits every
2 minutes until the Quick Talk latch mode
resets (an employee resets Switch 2).
TO PROGRAM LATCHING MODE:
NOTE: This example uses a Normally Open switch.
a. Pick up the telephone receiver and listen for the
acknowledge tone.
NOTE: To remove possible interference from prior
programming, in this application it is best to
use a Quick Talk unit set to factory defaults.
To restore factory defaults:
Dial "978" for VHF units; dial "979" for UHF units.
To program a different frequency than the default,
refer to page 7.
b. If you have a Normally Open switch, dial "814" to latch
the CLOSED condition on Switch 1. A beep indicates
the command is accepted.
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Page 14
250 Ohms
=
of resistance
i i
SWITCH 1
SWITCH 2
CURRENT LOOP
17.
SOLAR PANELS FOR
OPERATING & CHARGING NI-
CD BATTERIES
TO USE SOLAR POWER PANELS FOR OPERATION
AND FOR CHARGING INTERNAL NI-CD BATTERIES:
Follow the instructions in Section 19 for using Ni-Cd batter-
ies, including Step c. to enable the Battery Saver, and d. to
minimize the charging current needed. DO NOT EXCEED
15 Volts at the external battery terminals.
CALCULATING THE SOLAR PANEL SIZE:
Quick Talk uses little power when it is not transmitting. The
estimated time the unit does transmit can accurately
determine solar panel size requirements to charge Ni-Cd
batteries. The following formula sizes the panel properly:
EXAMPLE: Assume the Quick Talk transmits for one
minute of every hour, on average (1/60 hour).
Further assume the Quick Talk draws 150 mA
of current while transmitting (150 mA).
NOTE: 150 mA is a bit higher than real consumption;
the panel will be slightly oversized.
The formula to calculate required mA hours:
No. of hours
(
(1/60 hr.) x (150 mA) x
operation/ day
Plug the Example into the Formula:
(1/60 hour) (150mA) (24 hours/ day) = 60 mA hours/ day
RESULTS: In this Example, the Quick Talk solar panel
supplies 60 mA-hours in a 24-hour period.
NOTE: Study solar panel manufacturers' information.
c. Dial "312". Quick Talk sounds three short tones to
prompt you to begin speaking, then record the Switch 1
phrase, to be no longer than eight seconds.
EXAMPLE: Record "Help needed Paint Department."
d. Dial "5110" to suppress the Switch 1 OPEN message
(preventing transmitted messages when the sales
person resets the unit).
NOTE: Skip Step d. if it is desirable to send a
message when the unit is reset.
e. Dial "5124" to select 2 minutes as the message repeat
schedule for Switch 1 latched condition; refer to Table 9.
f. Dial "999", wait for the beep, then hang up the telephone
to complete the programming.
— TABLE 9 —
TIME BETWEEN
MESSAGES
........................
None/ Never
...................
On Changes Only
........................
30 seconds
...........................
1 minute
..........................
2 minutes
..........................
5 minutes
.........................
10 minutes
.........................
30 minutes
.............................
1 hour
............................
2 hours
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)
= Req'd. mA hr./ day
CODE NUMBER
0
—
1
DEFAULT
2
3
4
5
6
7
8
9
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