VXi VT1529A/B 사용자 설명서

Figure G-2 shows the block diagram of a more advanced algorithm that is 
favored in process control because of the flexibility allowed by its two 
differential terms. The "D" differential term is driven by changes in the 
process input measurement. The "SD" differential term is driven by changes 
in the setpoint variable value.

The PIDB algorithm provides clipping limits for its I, D, SD terms and the 
value sent to <outp_chan>. Values for these terms are not allowed to range 
outside of the set limits. The variables that control clipping are:

I term limits;

I_max and I_min

D term limits;

D_max and D_min

SD term limits;

SD_max and SD_min

<outp_chan> limits;

Out_max and Out_min

The PIDB algorithm provides Alarm Limits for the process variable PV 
and the Error term variable Error. If these limits are reached, the algorithm 
sets the value of <alarm_chan> true and generates a VXIbus interrupt. 
The variables that control alarm limits are:

Process Variable (from <inp_chan>); PV_max and PV_min
Error term alarm limits;

Error_max and Error_min

The max and min limits for clipping and alarms are set to 9.9E+37 and 
-9.9E+37 respectively when the algorithm is defined. This effectively turns 
the limits off until the values are changed with the ALG:SCALAR and 
ALG:UPDATE commands as described in "Pre-setting PID Variables and 
Coefficients" later in this section.

Setpoint

Variable

+

+

+

+ +

-

channel

channel

P_factor

Variable

Man_state

Variable

status .B4

Man_out

Variable

SD_factor

Variable

D_factor

Variable

I_factor

Variable

Σ

Σ

I_out

variable

D_out

variable

Error

variable

clip limits

status .B0

clip limits

status .B3

clip limits

status .B1

slew rate limited by

Man_inc variable

clip limits

status .B2

alarm limits

status .B6

SD_out

variable

manual

auto