11
7.2.2 Setting the 20 mA Level
The next, prompt will be the %T or ABS level assigned to the 20 mA
output level
(20MA)
on the lower row of the LCD display). Select the %T
level to assign to the
20MA
using the
and
buttons. Once the desired
level has been set, press the
button to accept it.
The factory default setting for %T is 100%T and for ABS is 2.
The 20 MA cannot be set lower than the 4 MA level.
NOTICE
7.2.3 Setting the Error Level
In case of an error in the AccUView LED, the 4-20 mA reading can be
used to indicate a problem by sending the output to either:
1. 4.00 mA,
2. 2.00 mA
3. 0 mA
4. OFF. In the case of OFF, the 4-20mA is unaffected by any error
condition.
The factory default setting is OFF. Select the desired ERLV by using the
and
buttons then press the
button to accept the desired error
response.
7.3 Configuring the RS–485 Port
If the instrument is wired for this option, and the I/O selection is changed to
485
, prompts will appear for setting the baud rate and the address.
7.3.1 Setting the Baud rate
Select the correct baud rate (1200, 2400, 4800, 9600, or 19200) for
operation of the I/O port by pressing the
or
buttons to change the
displayed baud rate.
The factory setting is 9600 baud.
Press the
button to continue on and select the desired instrument
address using the
or
buttons. Once the selection is satisfactory,
press the
button.
7.3.2 Setting the Address
The last selection is the address. This Address is important where multiple
instruments are wired on a single string. Each instrument MUST have a
unique Address.
The factory setting is Address 1
To enable the Modbus mode, select
ASCII
or
RTU
. For more information
refer to the Modbus Manual. The manual is also available as a free
download from our website at www.hfscientific.com.
7.4 Configuring the Alarms
Two relays are provided that are designed to operate as two independent
programmable alarms. Three types of information must be input to fully
program each alarm:
1. The alarm function (HI, LO, OFF or Error)
2. The alarm set point (level at which the alarm activates)
3. The delay time for the alarm: the time that the set point must be
exceeded prior to alarm activation and the time before resetting the
alarm (prevents chatter in the relay)
These three items are described below:
Alarm Function:
The alarms can either be turned OFF or programmed to
operate in one of three different manners:
1. HI alarm: the relay changes state when the measured %T or ABS
level is higher than the programmed alarm level for a prescribed
amount of time.
2. LO alarm: the relay changes state when the measured %T or ABS
level is lower than the programmed alarm level for a prescribed
amount of time.
3. Error: the relay changes state when a system error occurs. If a
system error occurs a message will appear on the lower row of the
screen describing the problem.
Alarm Set Point:
The level at which an alarm activates is called the
alarm set point. On the instrument, the alarm set point is designated as
“S/P”. The set point is adjustable to any valid %T or ABS level over the
range of the instrument in steps of 0.01 NTU.
Alarm Delay Time:
The alarm delay times are used to prevent ringing
of the alarm when the measured %T or ABS level is close to the set
point. The function of the delay times is as follows:
Delay On:
The %T or ABS level must exceed the alarm set point
continuously for at least this number of seconds before the alarm
activates.
If the delay on time is set at 5 seconds and the process %T or
ABS exceeds the set point continuously for only 4 seconds, the
alarm will not be activated. However, process %T or ABS exceeds
the set point continuously for 5 seconds or more, the instrument
will activate the alarm.
Delay Off:
The %T or ABS level must not exceed the alarm set point
continuously for at least this number of seconds prior to deactivation
of the alarm.
If the delay off time is set to 5 seconds and the process has
exited out of the alarm condition, the alarm will be reset only if the
process is out of the alarm condition for a continuous 5 seconds.
Otherwise, the instrument will still signal an alarm condition.