1-RELAY PROCESS 4-20 mA LOOP INDICATOR / MONITOR / WINDOW COMPARATOR OVER / UNDER PROTECTION with 4-20mA re-transmit
The input signal is converted and displayed as real-world values with up to 3 decimal places (eg 0-100.0°C ,not 4 -20mA).
The 4 -20mA re-transmitted signal is optically isolated from the input signal.
By default the re-transmittion parameters are set so that the output follows the input.
By setting the Span to a negative value, the device can be used as an inverter, generating a decreasing output signal as the input increases.
Maximum & Minimum values are logged for 24 hours (updated every 60 min).
The latch facility may be de-activated for one or both the relays allowing one relay to be used for control (not latched), and the other as a latched alarm.
Other features include adjustable signal damping, adjustable start-up and reaction delays, the ability to swap the relay’s functionality.
All settings may be locked & code protected to avoid changes from being made by unauthorised personnel.
The value displayed is re-transmitted based on the re-transmit ofset and span parameters.
The output may be set to correspond to the entire input range or any part thereof. eg.
An input signal of 0-100 °C may be re-stransmitted as received (4mA=0 °C, 20mA=100°C), or 50 - 70 °C (4mA=50 °C, 20mA=70 °C. set re-tx offset=50, span=20).
By setting the retransmit span to a negative value, the re-transmitted signal drops as the input signal rises, effectively inversing the signal.
The relays remain energised while the input signal is between the upper and lower set points.
Once de-energised, the signal must change in the opposite direction by the hysteresis amount before the relay will re-energise. (unless the latch terminals are shorted).
The signal is displayed as ‘real world’ values.(eg 0-100°C ,not 4 -20mA).
By setting the span to a negative value, the display will indicate lower values as the input rises.
The relay remains energised while the input signal is between the upper and lower set points.
Once de-energised, the signal must change in the opposite direction by the hysteresis amount before the relay will reenergise.
Note: the relay will NOT re-energise while the latch pins are shorted. The latch pins can also be used as a reset.
· The output 4-20mA is dependant on the value being displayed, and is set up in a similar manner to the display. The offset parameter determines when 4mA is output, and the span is the amount required for the output to increase by an additional 12mA ie. 20mA is output when the value displayed = re-transmit OFFSET+SPAN
· To set the re-transmittion signal to follow the input signal (the output 4-20mA follows the 4-20mA received), set the re-tx offset and span settings to the same value as the display offset and span settings.
· To set the re-transmittion signal to invert the input signal (the output = 4mA when the input = 20mA), set the re-tx offset = (display offset+span) and re-tx span = (display span x -1).
· Whenever the input signal is above or below the “CAL.O” or “CAL.S” values by more than 3%. The display indicates “Er.Hi” or “ER.Lo”.
· Certain settings are reset to default when the device is re-configured. Re check all settings to ensure they are correct before commissioning.
Display offset: -999 to 9999
Display span: -1999 to 9999
Display resolution: 0.01 to 1.000 (adjustable)
Input offset: 0 to 20.3mA
Input span: 0 to 20.3mA (offset + span maximum = 20.3mA)
Measurement resolution: 20 uA
Accuracy: ±0.3% @ 25°C (% of full scale)
Input voltage: ±15% of rated input