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. - Additional task
2-bit variables can be created in the System Manager.
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 = 9.174dec
Entry in index (Limit 2): 0x8000:14
(7.4 V / 10 V) x 216 / 2 - 1 = 24.247dec
Output:
Input channel 1 |
Index 0x6000:03 |
Index 0x6000:05 |
---|---|---|
1.8 V |
0x01hex, (Limit 1, limit value undershot) |
0x01hex, (Limit 2, limit value undershot) |
2.8 V |
0x03hex, (Limit 1, limit value reached) |
0x01hex, (Limit 2, limit value undershot) |
4.2 V |
0x02hex, (Limit 1, limit value exceeded) |
0x01hex, (Limit 2, limit value undershot) |
8.5 V |
0x02hex, (Limit 1, limit value exceeded) |
0x02hex, (Limit 2, limit value exceeded) |
Swap Limit index 0x80n0:0E
The limit function can be inverted by SwapLimitBits in index 0x80n0:0E.
Output Limit n (2-bit):
SwapLimitBits setting | Value |
---|---|
FALSE (default setting) |
|
TRUE |
|
The Swap limit function is available according to the table below
Terminal | Swap limit function from |
---|---|
EL31x1, EL31x4 | All firmware versions |
EL3112-0011 | All firmware versions |
EL3102 | Firmware 08 |
EL3112 | Firmware 08 |
EL3122 | Firmware 08 |
EL3142 | Firmware 08 |
EL3152 | Firmware 09 |
EL3162 | Firmware 08 |
EL3174, EL3174-00xx | All firmware versions |