The configuration of the individual characteristic of analog outputs
amounts to the introduction of suitable values X1, X2, Y1, Y2 in cor-
responding registers to them from the range 4007 – 4014
tab.3
. Values
introduced in these registers must be integral values corresponding to
set point values multiplied by the value 100.
4.3. RS-485 Interface
4.3.1. Description of the MODBUS Protocol Implementation
The implemented protocol is in compliance with the PI-MBUS-300
Rev G Modicon Company specification. Following functions of the
MODBUS have been implemented in P18 transducers:
Example 1
Configuration of the individual characteristic of the first current analog
output (temperature):
The temperature conversion in the range -12.25
o
C ÷ 77.75
o
C into the
analogue current signal from the range 4.5...18.5 mA is expected.
Exemplary Configuration of the
Individual First Analog Output Characteristik
Table 3
Name
Register address
Value
X1 temperature
4007
-1225
Y1 current
4008
450
X2 temperature
4009
7775
Y2 current
4010
1850
Code
Meaning
03 (03h)
Readout of n-registers
16 (10h)
Write of n-registers
17 (11h)
Identification of the slave device
Functions of the MODBUS Protocol Implemented
in P18 Transducers
Table 4