Settings

Selection of the analog signal type, index 0xF800:0n

In delivery state, all channels of the EP31xx are set for analog voltage measurement (-10 V …+10 V).

This setting can be made individually for each channel in the CoE object 0xF800:0n. Changes are immediately effective.

In the case of the EP31x2 the signal type -20 mA to +20 mA can additionally be selected (see illustration below).

Presentation, index 0x80n0:02

The measured value output is set in factory to two's complement representation (signed integer).
Index 0x80n0:02 offers the possibility to change the method of representation of the measured value.

• Signed integer representation

The negative output value is represented in two’s complement (negated + 1).
Maximum representation range with 16-bit = -32768 .. +32767_dec

Overview of further representations

• Unsigned integer representation

The output value is represented with 15-bit resolution without sign, therefore polarity detection is no longer possible.
Maximum representation range with 16-bit = 0 .. +32767_dec

• Absolute value with MSB as sign - representation

The output value is displayed in magnitude-sign format: MSB=1 (highest bit) in the case of negative values.
Maximum representation range with 16-bit = -32768 .. +32767_dec

Presentation types The presentation types Unsigned integer and Absolute value with MSB as sign have no function for unipolar modules. There is no change in the presentation in the positive range.

Siemens bits, index 0x80n0:05

If this bit is set, status displays are superimposed on the lowest three bits. In the error case "overrange" or "underrange", bit 0 is set.

Underrange and overrange, index 0x60n00:01, 0x60n00:02

Underrange and overrange is indicated as follows:

• The bits "Underrange", "Overrange" and "Error" in the process data are set.
• The "Error" LED of the affected channel lights up red.

The threshold values for the mentioned bits and the LED can be found in chapter Measuring ranges.

Limit 1 ad Limit 2, index 0x80n0:13, index 0x80n0:14

If the limits of the values that can be entered in indices 0x80n0:13 and 0x80n0:14 are violated, the bits in indices 0x60n0:03 and 0x60n0:05 are set accordingly (see sample below). The indices 0x80n0:07 or 0x80n0:08 serve to activate the limit value monitoring.

Output limit n (2-bit):

• 0: not active
• 1: Value < limit value
• 2: Value > limit value
• 3: Value = limit value

Limit evaluation The limit evaluation assumes a signed representation. The conversion to the desired representation (index 0x80n0:02) only takes place after the limit evaluation.

Linking in the PLC with 2-bit values PLC: IEC61131-PLC contains no 2-bit data type that can be linked with this process data directly. In order to transmit the limit information, therefore, define an input byte, e.g. and link the limit to the VariableSizeMismatch dialog as described in the chapter Process data. Additional task 2-bit variables can be created in the System Manager. Linking of 2-bit variable to additional task

Sample

Channel 1; Limit 1 and Limit 2 enabled, Limit 1 = 2.8 V, Limit 2 = 7.4 V, representation: signed integer

Entry in index (Limit 1): 0x8000:13
(2.8 V / 10 V) x 2¹⁶ / 2 - 1 = 9,174_dec

Entry in index (Limit 2): 0x8000:14
(7.4 V / 10 V) x 2¹⁶ / 2 - 1 = 24,247_dec

Output:

Swap Limit index 0x80n0:0E

The limit function can be inverted by SwapLimitBits in index 0x80n0:0E.

Output Limit n (2-bit):

The Swap Limit function is available according to the table below