This section explains Analog Tracking block configuration and how it affects block execution. The block can process up to 16 tracking conditions directly.
Configure tracking conditions from the dialog that opens from the Properties selection on a block's context menu. From the dialog you can add and modify conditions. By default, an AT block has one tracking condition but there can between 0 and 16 conditions.
In an instance of a class-based module, tracking conditions cannot be added or deleted, but their evaluation order can be changed and the number of conditions used (evaluated) can be set by the parameter T_USED_CND.
References to the I_OUT_D_n, P_OUT_D_n and F_OUT_D_n function block parameters are not updated when the Move Up and Move Down buttons are used to change the order of the conditions.
When condition n is True for longer than T_DELAY_ONn and T_DISABLEn is False, T_PRE_OUT_Dn and T_OUT_Dn are set. When condition n is True for less than T_DELAY_ONn, the timer resets until condition n evaluates to True again.
This functionality is similar to the CND function block.
T_OUT_Dn and T_PRE_OUT_Dn are set to True after T_DELAY_ONn is reached and remain True until condition n evaluates to False for longer than T_DELAY_OFFn. If the condition is True for less than T_DELAY_OFFn, T_OUT_Dn, and T_PRE_OUT_Dn remain True.
Condition n can be disabled only when T_HIGHER_MNGn is False.
When n is true, condition n logic evaluation is ignored and T_OUT_Dn is not set. The functionality is the same as the CND function block. However, when the expression evaluates to True, T_PRE_OUT_Dn is set and its value can be used in other logic.
When T_HIGHER_MNGn is True, T_OUT_Dn and T_PRE_OUT_Dn are equal regardless of the value of T_DISABLEn.
DISABLE_ACT and the bypass alarm are set as soon as at least one tracking condition is disabled. DISABLE_ACT is the logical OR of the T_DISABLEn parameters.
The outputs of the tracking conditions can be individually latched by setting the condition reset required parameter T_RESET_REQDn to True.
When T_RESET_REQDn is True, and T_OUT_Dn is True, and FDBK_IN > OUT + OUT_HYS or FDBK_IN < OUT - OUT_HYS, then T_L_OUT_Dn is set to True (when FDBK_IN status is bad, the latching occurs immediately when the first two conditions are satisfied). As long as T_RESET_REQDn is True, T_L_OUT_Dn remains True even if T_OUT_Dn returns to False or OUT - OUT_HYS ≤ FDBK_IN ≤ OUT + OUT_HYS.
When T_RESET_REQDn is False, T_L_OUT_Dn is a copy of T_OUT_Dn.
When all tracking conditions evaluate to False (including True conditions that are disabled), but at least one T_L_OUT_Dn remains True, block tracking reset required parameter RESET_REQD is set to True to indicate that there are no active tracking conditions (all T_OUT_Dn = False), but the block has to be reset to clear the latched tracking condition(s). Otherwise, RESET_REQD is False.
When T_RESET_REQDn is True, T_L_OUT_Dn returns to False only when T_OUT_Dn is False and RESET_D transitions from zero to a non-zero value. If T_OUT_Dn is True, T_L_OUT_Dn stays latched.
When T_RESET_REQDn is False, the parameter RESET_D has no effect on T_L_OUT_Dn.
When all T_L_OUT_Dn are False, RESET_REQD is set to False.
The Analog Tracking function block detects when one or more tracking conditions evaluate to True and sets the block outputs accordingly.
The tracking discrete output OUT_D is the logical OR of T_OUT_Dn and T_L_OUT_Dn. OUT_D is False when all the T_OUT_Dn and T_L_OUT_Dn parameters are False. OUT_D is True when at least one T_OUT_Dn or T_L_OUT_Dn is True.
OUT_INT is the unsigned 16-bit binary weighted output value that represents the bit combination of T_OUT_Dn or T_L_OUT_Dn. OUT_INT is non-zero when at least one T_OUT_Dn or T_L_OUT_Dn is True.
The value of OUT is either 0 or the value of one of the condition track values (T_VALn).
When all the T_L_OUT_Dn parameters are False, OUT_INT is zero and OUT is also zero.
When only one tracking condition n is active or latched (T_L_OUT_Dn is True), OUT is equal to T_VALn.
When more than one tracking condition is active or latched, OUT is equal to the T_VALn parameter associated with the active or latched tracking condition having the smallest condition number. Therefore, configure the tracking condition that has the highest priority as condition 1. OUT is recalculated each scan.
If the status of the tracked signal is Bad, error options exist to continue tracking the bad value, to stop tracking, or to use the last good value.
When all the T_VALn parameters of the configured tracking conditions have the same value, the configuration order of the tracking conditions has no importance.
When FDBK_IN status is bad, the FIRST_OUT trap occurs immediately when the first two conditions are satisfied.
FDBK_IN can be connected to the OUT parameter of the downstream PID block, and it corresponds to the command provided by the PID block.
When the trap occurs, FIRST_OUT is the bit value of the highest priority condition (lowest condition number) that is currently active.
FIRST_OUT retains its value until it is reset or another condition that has a different track value (T_VALn) and a higher priority becomes active. FIRST_OUT changes to the bit value of the newly active condition.
If trapping is required under certain conditions only, configure a CND function block and wire its output OUT_D to the ARM_TRAP parameter of the Analog Tracking function block.
If the first out output should not be updated after the first trap that occurred since the last reset, even if FDBK_IN > OUT + OUT_HYS or FDBK_IN < OUT - OUT_HYS, configure the expression of a CND block to AT/FIRST_OUT = 0 and wire the OUT_D of the CND block to the input ARM_TRAP of the AT block.
If FDBK_IN status is bad, there is no auto reset for FIRST_OUT and it must be manually reset.
After a reset, FIRST_OUT remains zero until the next trap occurs.
When the value of FIRST_OUT is zero, its status is GoodNonCascade.
When RESET_D transitions from zero to a non-zero value, FIRST_OUT is cleared and the tracking conditions that are latched and no longer active are unlatched.
If RESET_D is True, it is set to False at the end of execution.