GF U1000 V2 Wallmount WM Instrucciones De Uso página 22

Electrical connection & outputs
5.6.4 Flow alarm – signal loss
If the flow reading (signal) is lost, as indicated by the flow rate being displayed as "-----", the alarm will be triggered. The default
setting is normally open, but the user can select between N/O and N/C.
5.7 Current / 4-20 mA output
The default 4-20mA output setting is OFF, and the 4-20mA LED on the keypad will not be illuminated. The default flow for 20mA
output will be automatically set depending on the pipe size. The default flow for 4mA is 0. This can be changed, see section Current
output menu (4 to 20 mA versions only).
If the flow reading is greater than that set as the 20mA value, or there is negative flow, or no flow signal can be detected, then an
alarm current of 3.5mA will generated.
NOTICE
The 4 to 20mA current output is factory calibrated.
5.7.1 Current / 4-20 mA output connections
The GF U1000 V2 WM/WHM unit can be optionally configured with a 4-20mA output. The isolated 4-20mA is a current source and
can drive into a maximum load of 620Ω.
If fitted, the 4-20mA current outputs are available at the terminal block labelled IO0 4-20mA with RET and OUT connections. The
alarm current due to a flow outside the range specified or due to a loss of signal is set at 3.5mA.4-20 mA, Pulse option
NOTICE
This output is suitable for SELV circuits only
Electrically this is a Volt, or potential free contact and, when selected as a low flow alarm, is configurable NO/NC.
5.8 Modbus output
The Modbus RTU interface is configured via the Modbus sub menu in the password controlled menu.
• The data rate can be selected in the range 1200 to 38400 baud.
• The address can be set in the range 1 to 126.
• Polling Rate 1000ms (1sec). Time out after 5 seconds.
• The instrument responds to the "read holding registers" request (CMD 03).
• If the flow reading is invalid then the flow value will be zero.
• If a temperature sensor goes out of range then the value will go to -11 °C (12.2 °F).
• Float byte order –AB CD – Big endian – MSB first.
• On a unit set to Imperial the temperature is in °F, Power is in BTU/s and flow in US Gallons.
• The GF U1000 V2 WM/WHM complies with the Modbus specification document:
http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf
Both of these faults will set the relevant status bit. The following registers are available.
On a unit set to Imperial the flow in US Gallons.
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User Manual