Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 32)

Publication 1757-UM006A-EN-P - May 2002
1-18 The Fieldbus Communication Model
Discrete Output Block
Figure 1.9 Functional Schematic for Discrete Output Function Block
Table 1.I Discrete Output Block Specifications
Description The Discrete Output function block converts the value in SP_D to something useful for the hardware linked to the
CHANNEL selection. A functional schematic of the block is shown in Figure 1.9 for reference.
Function Notes
• Supports Out of Service (OOS), Local Override (LO), Manual (Man), Automatic (Auto), Cascade (Cas), and Remote
Cascade (RCas) modes.
• The Set point (SP_D) supports the full cascade sub-function.
• Use the Cascade mode to transfer the output of another block to the Set point (SP_D) of the DO block.
• Use the IO_OPTS Invert selection to do a Boolean NOT function between the field value and the output.
• Use the IO_OPTS Invert selection to do a Boolean NOT function between the SP_D and the output.
• If the hardware supports a readback value, it is used for READBACK_D, and, after accounting for the IO_OPTS
Invert selection, acts as the PV_D for this block. If this is not supported, READBACK is generated from OUT_D.
• In the Man mode, an operator can force the output, in a programmable logic controller sense. If Man mode is not
permitted, it must be supported as a transition mode for exiting the OOS mode
• The SIMULATE_D parameter is for testing purposes only and always initializes in the disabled state.
Parameters
(see Appendix A
for definitions of
each parameter) ALERT_KEY
BKCAL_OUT_D
BLOCK_ALM
BLOCK_ERR
CAS_IN_D
CHANNEL
FSAFE_TIME
FSAFE_VAL_D
GRANT_DENY IO_OPTS
MODE_BLK
OUT_D
PV_D
PV_STATE
RCAS_IN_D
RCAS_OUT_D
READBACK_D
SHED_OPT ST_REV
STATUS_OPTS
STRATEGY
TAG_DESC
UPDATE_EVT
XD_STATE
SIMULATE_D
SP_D
DO
Transducer
OUT_D
Simulate
SIMULATE_D
Optional
Invert
Optional
Invert
Output
CHANNEL
OUT_D
Mode
SHED_OPT
SP_D
CAS_IN_D
RCAS_IN_D
BKCAL_OUT_D
RCAS_OUT_D
Setpoint
Failsafe
FSAFE_TIME
FSAFE_VAL_D
READBACK_D
PV_D
BKCAL_OUT_D
RCAS_OUT_D
CAS_IN_D
RCAS_IN_D