Red Lion PAX2S - Manual (Page 26)

26
RECEIVING DATA FROM THE METER
Data is transmitted by the meter in response to either a transmit command (T),
a print block command (P) or User Function print request. The response from
the meter is either a full field transmission or an abbreviated transmission. The
meter response mode is selected in Serial Port Parameters (Abrv).
Full Field Transmission (Address, Mnemonic, Numeric data)
Byte Description
1, 2 2 byte Node Address field [00-99]
3 <SP> (Space)
4-6 3 byte Register Mnemonic field
7-18 2 byte data field, 10 bytes for number, one byte for sign, one byte for
decimal point
19 <CR> carriage return
20 <LF> line feed
21 <SP>* (Space)
22 <CR>* carriage return
23 <LF>* line feed
* These characters only appear in the last line of a block print.
The first two characters transmitted are the node address, unless the node
address assigned = 0, in which case spaces are substituted. A space follows the
node address field. The next three characters are the register mnemonic.
The numeric data is transmitted next. The numeric field is 12 characters long
(to accommodate the 10 digit totalizer), with the decimal point position floating
within the data field. Negative values have a leading minus sign. The data field
is right justified with leading spaces.
The end of the response string is terminated with a carriage return <CR> and
<LF>. When block print is finished, an extra <SP><CR> <LF> is used to
provide separation between the blocks.
Abbreviated Transmission (Numeric data only)
Byte Description
1-12 12 byte data field, 10 bytes for number, one byte for sign, one byte for
decimal point
13 <CR> carriage return
14 <LF> line feed
15 <SP>* (Space)
16 <CR>* carriage return
17 <LF>* line feed
* These characters only appear in the last line of a block print.
Meter Response Examples:
1. Node address = 17, full field response, Input = 875
17 INP 875 <CR><LF>
2. Node address = 0, full field response, Setpoint 2 = -250.5
SP2 -250.5<CR><LF>
3. Node address = 0, abbreviated response, Setpoint 2 = 250, last line of block
print
250<CR><LF><SP><CR><LF>
Auto/Manual Mode Register (MMR) ID: U
This register sets the controlling mode for the outputs. In Auto Mode (0) the
meter controls the setpoint and analog output. In Manual Mode (1) the outputs
are defined by the registers SOR and AOR. When transferring from auto mode
to manual mode, the meter holds the last output value (until the register is
changed by a write). Each output may be independently changed to auto or
manual. In a write command string (VU), any character besides 0 or 1 in a field
will not change the corresponding output mode.
U abcde
e = Analog Output
d = SP4
c = SP3
b = SP2
a = SP1
Example: VU00011 places SP4 and Analog in manual.
Analog Output Register (AOR) ID: W
This register stores the present signal value of the analog output. The range
of values of this register is 0 to 4095, which corresponds to the analog output
range per the following chart:
Register
Value
Output Signal*
0-20 mA 4-20 mA 0-10 V
0 0.00 4.00 0.000
1 0.005 4.004 0.0025
2047 10.000 12.000 5.000
4094 19.995 19.996 9.9975
4095 20.000 20.000 10.000
*Due to the absolute accuracy rating and resolution of the output card, the
actual output signal may differ 0.15% FS from the table values. The output
signal corresponds to the range selected (0-20 mA, 4-20 mA or 0-10 V).
Writing to this register (VW) while the analog output is in the Manual Mode
causes the output signal level to update immediately to the value sent. While in
the Automatic Mode, this register may be written to, but it has no effect until the
analog output is placed in the manual mode. When in the Automatic Mode, the
meter controls the analog output signal level. Reading from this register (TW)
will show the present value of the analog output signal.
Example: VW2047 will result in an output of 10.000 mA, 12.000 mA or
5.000V depending on the range selected.
Setpoint Output Register (SOR) ID: X
This register stores the states of the setpoint outputs. Reading from this
register (TX) will show the present state of all the setpoint outputs. A “0” in the
setpoint location means the output is off and a “1” means the output is on.
X abcd
d = SP4
c = SP3
b = SP2
a = SP1
In Automatic Mode, the meter controls the setpoint output state. In Manual
Mode, writing to this register (VX) will change the output state. Sending any
character besides 0 or 1 in a field or if the corresponding output was not first in
manual mode, the corresponding output value will not change. (It is not
necessary to send least significant 0s.)
Example: VX10 will result in output 1 on and output 2 off.