SENDING COMMANDS TO THE IMP
When sending commands to the unit a command string must be constructed.
The command string may consist of command codes, value identifiers, and
numerical data. Below is a table outlining the codes the indicator will recognize.
COMMAND FUNCTIONS
T transmits the requested information specified by the identifier
(A-I, K, and L)
V change a value specified by the identifier (C-F, K, and L)
N address a particular indicator in a multiple unit loop (0-99)
R reset a value specified by the identifier (B-D, G, H, I, and J)
P print per programmable print options (A-H)
VALUE IDENTIFIERS SERIAL MNEMONICS
A input or process value INP
B totalizer TOT
C alarm #1 AL1
D alarm #2 AL2
E hysteresis #1 HS1
F hysteresis #2 HS2
G peak reading PEK
H valley reading VAL
I zero tare TAR
J tare input —
K analog low ANL
L analog high ANH
Note: RJ - tares the input (rezeros). When the input is tared (via front panel or
“RJ”) the amount is stored in the tare reading (I). Ex. When a tare is
performed, the display reads “5.0”, the tare value will be “-00005.0” (and the
display will show 0.0).
A command string is constructed by using the above commands and identifiers
along with any data values that are required. The indicator will accept “+” or “-”
in front of the data value. Numbers without “+” are understood to be positive.
Leading zeros can be eliminated and both lower and upper case characters are
accepted. The address command is used to allow a command to be directed to a
specific unit on the loop. If the indicator is assigned an address of “0”,
transmission of the address command is not required. This is done where only
one indicator is in the loop.
The command string is constructed in a specific logical sequence. The
indicator will reject command strings that do not conform. Only one operation
can be performed per command string. Below is a description of how to construct
a command string.
1. If the indicator has an address other than zero, the first two characters of the string
must consist of the address command (N) followed by the unit address number
(0-99). If the indicator has an address of 0, the address command is optional.
2. The next two characters in the string are the actual command the indicator must
perform and the identifier on which it operates. The command P - print, has an
implied operation and needs no value identifier.
3. If the change value command is being used (V), the next characters in the string
after the value identifier, are the numerical data. When sending numerical data,
such as change an alarm value, the correct number of digits to the right, must be
included. As an example, to change an alarm value from 750.02 to 500.0. Sending
500 would cause the indicator to see 50.0 and change the alarm value accordingly.
4. All commands must be terminated by an asterisk(*). The indicator will not
respond to any other code. Carriage return and line feed are not valid
terminators and should be suppressed with the character “;”, if using a BASIC
print statement (ex. Print “N9TA*”;).
COMMAND STRING EXAMPLES
Indicator with address 3, transmit input reading.
N3TA*
Indicator with address 0, change alarm #1 to 1500.
VC1500*
Indicator with address 1, reset totalizer.
N1RB*
Indicator with address 99, print the print options.
N99P*
Indicator with address 0, zero tare value.
RI*
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