GE 90-30/20/Micro Retentive Coil (M) , Negated Retentive Coil (/M) , Positive Transition Coil () , Negative Transition Coil ()

GFK-0467K Chapter 4 Series 90-30/20/Micro Instructions Set 4-5

Retentive Coil —(M)—

Like a normally open coil, the retentive coil sets a discrete reference ON while it receives power

flow. The state of the retentive coil is retained across power failure. Therefore, it cannot be used

with references from strictly non-retentive memory (%T).

Negated Retentive Coil —(/M)—

The negated retentive coil sets a discrete reference ON when it does not receive power flow. The

state of the negated retentive coil is retained across power failure. Therefore, it cannot be used with

references from strictly non-retentive memory (%T).

Positive Transition Coil —(↑↑)—

If the reference associated with a positive transition coil is OFF, when the coil receives power flow

it is set to ON until the next time the coil is executed. (If the rung containing the coil is skipped on

subsequent sweeps, it will remain ON.) This coil can be used as a one-shot.

Each reference should only be used as a transition coil once in the application program, so as to

preserve the one-shot nature of the coil.

Transitional coils can be used with references from either retentive or non-retentive memory (%Q,

%M, %T, %G, %SA, %SB, or %SC).

Negative Transition Coil —(↓↓)—

If the reference associated with this coil is OFF, when the coil stops receiving power flow, the

reference is set to ON until the next time the coil is executed.

Each reference should only be used as a transition coil once in the application program, so as to

preserve the one-shot nature of the coil.

Transitional coils can be used with references from either retentive or non-retentive memory (%Q,

%M, %T, %G, %SA, %SB, or %SC).

Example:

In the following example, when reference E1 goes from OFF to ON, coils E2 and E3 receive power

flow, turning E2 ON for one logic sweep. When E1 goes from ON to OFF, power flow is removed

from E2 and E3, turning coil E3 ON for one sweep.

| E1 E2

|——| |—————————————————————————————————————————————————————————————————(↑↑)—

| E1 E3

|——| |———————————————————————————————————————(↓↓)—