Answer / carl_ellis

Smart vs Conventional transmitters

Conventional

A conventional 4-20ma transmitter regulates the loop
current and provides only a process variable signal.

The zero and span adjustments are analog adjustments. n
the case of fixed range transmitters the zero and span
adjustments are limited to about plus/minus 2-3% of the
fixed zero or span values. Some conventional transmitters
have an adjustable turndown range, but calibrating a
turndown range requires a simulated process variable (an
applied calibration pressure or a simulated temperature
(RTD or thermocouple) electrical signal). Turndown is
generally limited to about 5:1 or 6:1.

Smart

A smart transmitter provides a process signal but can also
send/receive information about the instrument itself, e.g.
zero and span info, tag (instrument loop identification),
diagnostics, or even multiple process variables using a
digital protocol.

Configuration changes are done either with a keypad and
display or through a protocol like HART, which is
superimposed on the 4-20mA signal, so no additional wiring
is needed for smart communication. HART communication is
accomplished with a handheld communicator or a modem and
software.

Turndown rangeability can be as high as 100:1 (with reduced
accuracy at the low end); 15:1 or 20:1 with stated accuracy
and can be accomplished without applying an external
calibration signal, reference or supply.

Smart transmitters can communicate via a Fieldbus,
Foundation Fieldbus or Profibus.

Carl Ellis
Measure First

what is protonics how it is differ from electronics

1 Answers  

---

How is PH sensor works ?

0 Answers  

---

why the derivative in PID is always set to zero?

3 Answers  

---

when the instrument tapping on pipe line is located below and transmitter is located above the tapping point for liquid service transmitter, what should we do, is there any additional drain valve is required??

0 Answers  

---

what is the input of digital counter during the the calibration time?

0 Answers  

---

we are used SAMSON 3730 Smart positioner.please tell me how to calibration this.

1 Answers   TCCL,

---

what is difference between E/P positioner and I/P positioner. Why E/P fixed in below actuator and why I/P fixed in other place

1 Answers  

---

how to calculate flow range in DP tx

1 Answers   Karnataka Power,

---

Why humidity limit is 30 to 55 % for raw material storage?

1 Answers  

---

What is the use instrument barriers? Can you give me review materials about this?

1 Answers  

---

what is the safety integrity levels (SIL)

1 Answers  

---

What is procedure on mmwc in to tph

2 Answers  

---