Limit 1 and limit 2, Swap Limit Bits

Limit 1 and limit 2, index 0x80n0:13, index 0x80n0:14

If the value exceeds or falls below these values, which can be entered in the indices 0x80n0:13 and 0x80n0:14, then the bits in the indices 0x60n0:03 and 0x60n0:05 are set accordingly (see example 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 is smaller than the limit value
• 2: Value is larger than the limit value
• 3: Value is equal to the 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 The limit information consists of 2 bits. Limitn can be linked to the PLC or a task in the System Manager.

• PLC:
  IEC61131-PLC contains no 2-bit data type that can be linked with this process data directly. For transferring the limit information, define an input byte (e.g. see Fig. Input byte definition) and link the limit to the VariableSizeMismatch dialog, as described in section Note about the 1-byte status of earlier EtherCAT Terminals.

Fig.222: Input byte definition

• Additional task
  2-bit variables can be created in the System Manager.

Fig.223: Linking of 2-bit variable to additional task

Example for EL3162:

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