Infinite Peripherals SCOM-100 - Manual (Page 19)

SCOM-100, User guide 19
The 4-20mA input signal is converted by the internal A/D converter in the digital raw
range of 819 to 4095.
The following diagram illustrates the conversion characteristic:
The conversion values are given by the formula:
Raw digital value:=4095 * Ix/20
Ix: Input current value (mA)
According to the formula, a 4mA input is converted to:
Raw digital value=4095*4/20 = 819
This is the value setting for SSL.
A 20mA input is converted to a raw reading of 4095.
This is the value setting for SSH.
SCOM-100 physical scale values are limited to integer values between -100,000 and
100,000. It is reasonable to select the physical scale in the range of 0 to 10,000 mBar
to gain a better resolution.
The configuration command would then be:
1200,0,2,Pressure,819,4095,0,10000,2500,8500,mBar,15
The low alarm limit is set to 2.5 Bar, the high alarm limit to 9.5 Bar. A 15 second delay
is also set so that the input signal must persist in value and exceed alarm limits (low or
high) for 15 seconds. If these clauses are met then an alarm SMS will be initiated.
Note: Alarm annunciation is cancelled if the respective Scale (low or high) and limit
alarm values (low or high) are equal.
4.5.2 Setting alarm message’s texts for analog inputs
A similar command to the one for digital inputs is available to associate low and high
alarm events with respective SMS messages (1-128 messages, see 4.3.1).
The configuration command is:
1201,m,n,ID1,ID2
1201: Command ID
m: Module number (0 for SCOM-100 main unit, 1-4 for AI-4 expansion
units)
n: Input number (1-2 for SCOM-100 main unit, 1-4 for AI-4 expansion units)
ID1: ID number 0-128 of the message’s text for exceeding the low limit
ID2: ID number 0-128 of the message’s text for exceeding the high limit
Note: ID1/ID2 value 0 means no message.