E/I - External/Internal Transfer Switch - Siemens 353 User Manual

Function Blocks

3.2.37 E/I - External/Internal Transfer Switch

E/I function blocks can be used on a one per loop
basis to select an analog signal, connected to input E
(External) or input I (Internal), as a setpoint for the
loop controller.
The position of the E/I switch can be changed on each
positive transition of input ST and will normally be
connected to the PS output of pushbutton block
PB2SW, configured for momentary action. The SE
output will normally be connected to the MD input of
pushbutton block PB2SW. E/I switch position will be
shown on the operator faceplate by a lighted LED:
green for E, red for I.
The E/I switch position can also be changed by an
operator HMI command over the Modbus RS485 or
Modbus/TCP Ethernet networks.
When PU LAST is set to YES, the E/I switch will
power up in the last position during a hot or a warm
start. During a cold start, it will power up in the position set by the POWER UP parameter. If PU LAST is set to
NO, the E/I switch will power up in the last position during a hot start, but during a warm or cold start will power
up in the position set by the POWER UP parameter.
The IO (Internal Override) input enables a HI (1) input to temporarily select the Internal Input as the function block
output O1. This input does not affect the position of the E/I switch.
Outputs SE and SI indicate the actual position of the E/I switch. SE is HI (1) when in the E position and LO (0)
when in the I position. SI is HI when in the I position and LO when in the E position. Outputs IS and ES indicate
the actual source of the block output. IS is HI when O1 is the Internal input and is LO when O1 is the External
input. ES is HI when O1 is the External input and is LO when O1 is the Internal input.
3-42
EI Transfer Switch
Switch Transfer
ST
Switch Control
1
0
0
1
E
External
E/I
I
Internal
IO
Internal Override
BLOCK DIAGRAM
E/I TRANSFER SWITCH
E/I
Switch Transfer ST
E/I
E
External Input
TRANSFER SWITCH
Internal Input I
Internal Override IO
P O W E R U P
POWER UP position
P U L A S T
Power Up LAST
I N P U T S T
INPUT ST
I N
P U T E
INPUT E
(H)
I N P U T
I
INPUT I
(H)
I N P U T I O
INPUT IO
(H)
S
E N
Exec. Seq. No.
Network Command
Switch position E
Switch position I
Output 1
Internal Status
External Status
UM353-1B
ESN = 000
O1
Output 1
SE Switch position E
Switch position I
SI
IS Internal Status
External Status
ES
......................... E/I (I)
(S)
....................... NO/YES (YES)
(S)
............. loop tag.block tag.output (null)
(H)
...............
loop tag.block tag.output (null)
.................
loop tag.block tag.output (null)
..............
loop tag.block tag.output (null)
...................... 001 to 250
(H)
SE
SI
O1
IS
ES
April 2012