User manual for RTD,TC,mV/4-20mA converter module SPT-86L
when the measured value is increasing the output current is decreasing).
Parameters ”
OutLoRange
” and ”
OutHiRange
” define the permissible output current
range beyond the nominal range 4-20 mA. If the calculated current
I
out
would exceed the
permissible range, the output would generate current equal to the upper or lower border of the
range. Parameter ”
OutLoRange
” defines the lower border of the range due to formula:
I
min
= 4 mA - 4 mA × ”
OutLoRange
” %
Parameter ”
OutLoRagne
” can be set from 0 to 29.9%. Parameter ”
OutHiRange
” defines the
lower border of the range due to formula:
I
max
= 20 mA + 20 mA × ”
OutHiRange
” %
Parameter ”
OutHiRange
” can be set from 0 to 19.9%.
The minimum current which can flow in the current output's circuit is about 2.5 mA. It
occurs when the current output is disabled (parameter ”
OutMode
”). This is the current
needed to power the current output circuit.
Parameter ”
OutAlarm
” defines how the current output reacts in the critical situation
(exceeding the permissible range, shorting or opening measuring inputs). In such a situation
the output current will be unchanged or will be set to the desired value (depending on the
parameter ”
OutAlarm
”).
•
Critical situation is signalized by the red LED (labeled
ERROR
).
•
After resolution of the critical situation output current returns to the value
determined on the basis of the measurement result.
•
Before turning off the device it is recommended to first disable the current output's
power supply, and then the device itself. If the current output is supplied while the
device itself is turned off, the output current will be about 27.5 mA.
5.3.
FORCING OF ADDRESS FFH
New devices has set to Modbus addresses FEh. To enhance system installation process
special operation mode has been developed. It allows to force address FFh in single module
using internal momentary switch mounted on module mainboard (fig. 4.1). Switch is accessible
through a small hole in .the front panel.
To change address of the device to FFh, wait for a moment after power up until green
LED (RUN) starts flashes. Next press and hold push-button about 4 seconds until green LED
will lights permanently, then release push-button.
The device changes its MODBUS address to FFh and waits for a new address
(readdressing). Green LED (RUN) stay permanently on until readdressing via RS-485, or
power off. While module is in this state it is possible to control its inputs, and communication is
possible using temporal address FFh.
At this moment MASTER controller should find new device and readdress it (to address
other than FFh and FEh). After remote readdressing green LED indicator starts to flashes
again.
Simultaneously with change of device address, its baud rate is changed to
9600 bit / s.
Required transmission speed (1200 bit/s. to 115200 bit/s.) can be set by write to
register 22h. After change of transmission speed the device sends the answer with new baud
10
i
i
