Analog Output, Modbus and HART

The 0 - 20 mA output is equivalent to the following analog output:

Condition	Modbus	HART (Normal)	HART (Special)
Startup	0 - 0.2 mA	3.5 ±0.2 mA	1.25 ±0.2 mA
Fault	0 - 0.2 mA	3.5 ±0.2 mA	1.25 ±0.2 mA
COPM Fault	2.0 ±0.2 mA	3.5 ±0.2 mA	2.0 ±0.2 mA
Ready	4.05 ±0.2 mA	4.05 ±0.2 mA	4.05 ±0.2 mA
IR	8.0 ±0.2 mA	8.0 ±0.2 mA	8.0 ±0.2 mA
UV	12.0 ±0.2 mA	12.0 ±0.2 mA	12.0 ±0.2 mA
Alarm Low	16.0 ±0.2 mA	16.0 ±0.2 mA	16.0 ±0.2 mA
Alarm High	20.0 ±0.2 mA	20.0 ±0.2 mA	20.0 ±0.2 mA

The maximum analog output load, including wiring, is 600 ohms.

In normal HART mode, the current output does not go below 3.5 mA. Modbus sends 2.0 mA output for COPM (as if HART was not there) to make a constant Modbus program available. The digital HART protocol sends the actual current output. When the Alarm High or Alarm Low relays are latched, the highest output current is also latched. The output current goes back to 4.0 mA when the Alarm Reset switch relay is activated.

The special HART mode lets the current decrease to 1.25 mA. The HART protocol continues to operate. Use the special HART mode with products that require 2 mA output for COPM, 1.5 mA output when the device is offline, and 0 mA output for a Fault condition.

The Modbus protocol is used to configure the device or to find the status of the device.

For information about Modbus, refer to the FL500 Modbus Communication Operating Manual (PN 10193214).

For information about HART, refer to the FL500 HART Communication Operating Manual (PN 10193215).

TB1 Position	Connection
6	DATA +
7	DATA -