Signal Output; Serial Output; Analog (4-20 Ma) Outputs And Communications (Pl5 - Green) - Michell Instruments XTP601 User Manual

INSTALLATION
4.5.3

Signal Output

There are two 4-20mA linear signal output channels. Both are for oxygen concentration.
One is fixed on the calibrated range of the unit and the second can be configured
in the menu. NOTE: When the instrument is warming up (cell temperature
not stabilized) these outputs are factory set to 3.2 mA to indicate that the
instrument is not ready.
• The maximum mA output is approximately 20.5mA
• The minimum mA output is approximately 3.8mA
• The user can select the falut conditon to drive the mA output Low (3.2mA)
or Hi (21.4mA).
4.5.4

Serial Output

The analyzer has Modbus RTU communications over RS485 protocol; please see
Application Software CD for more details.
• Type: Modbus RTU over RS485
• RS485: 2 wire (plus ground), half duplex
• Baud Rate: 9600
• Parity: None
• Data bits: 8
• Stop bits: 1
4.5.5

Analog (4-20 mA) Outputs and Communications (PL5 - Green)

Warning: Do not attempt to loop-power this instrument via the 4-20 mA
output as this will irreversibly damage the main pcb.
PIN 7
RS485
GND
NOTE 1: Channel 1 is fixed range output over instrument range and Channel
2 is adjustable between 0-100%.
NOTE 2: For long cable lengths, a termination resistor of 120Ω is provided to
aid in impedance matching of the communications cable. This is selectable
via JMP3. A terminating resistor is simply a resistor placed at the extreme
end or ends of a cable on an RS485 network to reduce effects of impedance
mismatch. Impedance mismatch can cause reflections of data as it passes
down the cable and the reflections could be large enough to cause data errors.
NOTE 3: The maximum loop load resistance for mA outputs is 550Ω
NOTE 4: the mA outputs are powered with a 24V excitation voltage.
32
PIN 6 PIN 5
RS485 RS485
B A
XTP601 User's Manual
PIN 4 PIN 3
Ch2 Ch2
O/P O/P
- +
97313 Issue 5, May 2018
PIN 2 PIN 1
Ch1 Ch1
O/P O/P
- +