7.20
SEL-787 Relay Instruction Manual Date Code 20150130
Communications
SEL ASCII Protocol and Commands
NOTE: 0% = low span, 100% = high
span. For a scaled output from
4–20 mA, 0 percent is 4 mA and
100 percent is 20 mA.
When parameter p is a percentage, the relay displays the following message
during the test:
Outputting xx.xx [units] to Analog Output Port for y.y
minutes. Press any key to end test
When parameter p is a ramp function, the device displays the following
message during the test:
Ramping Analog Output at xx.xx [units]/min; full scale in
y.y minutes. Press any key to end test
For either mode of operation (percentage or ramp), when the time expires, or
upon pressing a key, the analog output port returns to normal operation and the
device displays the following message:
Analog Output Port Test Complete
Example 1
The following is an example of the device response to the ANA command in
the percentage mode. For this example, we assume the analog output signal
type is 4–20 mA, and we want to test the analog output at 75 percent of rating
for 5.5 minutes. To check the device output, calculate the expected mA output
as follows:
To start the test, enter ANA A0301 75 5.5 at the Access Level 2 prompt:
Example 2
The following is an example of the ramp mode when the analog output signal
type is 4–20 mA for a 9.0 minute test. To check the device output, calculate
the current/time (mA/min) output as follows:
Table 7.9 ANALOG Command Format
Parameter Description
c Parameter c is the analog channel (either the channel name, e.g., A0301, or
the channel number, e.g., 301).
p Parameter p is a percentage of full scale, or either the letter “R” or “r” to
indicate ramp mode.
t Parameter t is the duration (in decimal minutes) of the test.
where:
xx.xx
is the calculation of percent of full scale
[units]
is either mA or V, depending on the channel type setting
y.y
is the time in minutes
where:
xx.xx
is the calculation based upon range/time t
[units]
is either mA or V, depending on the channel type setting
y.y
is the time in minutes
=>>ANA A0301 75 5.5 <Enter>
Outputting 16.00 mA to Analog Output Port for 5.5 minutes.
Press any key to end test
Output 20.00 mA 4.00 mA–
75
100
---------
4.00 mA+ 16.00 mA==
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