Rockwell Automation 1785-Vx0B, D17856.5.9 PLC-5 VME VMEbus Programmable Controllers User Manual - Manual (Page 61)

Chapter 4
Ladder-Program Interfaces
4-14
Word Explanation Function Code
15 3 TDS To-VME data size If 0, the continuous-copy-to-VME operation does D16 VMEbus transfers; if 1, it does D08(EO)
transfers.
15 3 TERROR To-VME error code If nonzero, refer to NO TAG for the most-recent error.
17 3 TADDRESS (HI BYTE) Meaningful only if TAM=1 Address bits 23-16 of the address of the first byte of the VMEbus destination .
18 3 TADDRESS VMEbus destination Address bits 15-0 of the address of the first byte of the VMEbus destination.
19 3 TLENGTH To-VME copy length The number of 16-bit words to be transferred by the continuous-copy-to-VME operation.
20 3 TFILE To-VME file number The number of the processor source file of the continuous-copy-to-VME operation.
21 3 TELEMENT To-VME element number The number of the first element to be transferred in the source file of the continuous-copy-to-
VME operation.
22 3 TINT To-VME interrupt If nonzero, the VMEbus interrupt level of the interrupt to be generated after completion of each
continuous copy to VME operation.
000 specifies no interrupt,
001 specifies interrupt level 1,
010 specifies level 2,
...,
111 specifies level 7.
23 3 TSTATUSID To-VME status/ID The VMEbus status/ID value transmitted during interrupt acknowledge cycles of the
above interrupt.
3 Both lPLC ladder logic and the VME host computer can write to the status file fields that control the continuous-copy-to function. When both the ladder program and the host computer try to update the
status file simultaneously, the ladder program overwrites the changes made by the host.
24 4 IRQxE Interrupt x enabled If bit x is 1, the PLC-5/VME processor is an interrupt handler for interrupt IRQx. If IRQx is
asserted, the PLC-5/VME processor will perform a VMEbus interrupt acknowledge cycle, store the
interrupt status/ID received in IRQxSID, and set bit IRQxR.
24 4 IRQxR Interrupt x received If bit x is 1, the PLC-5/VME processor has accepted a VMEbus interrupt for IRQx since bit IRQxR
was last 0.
4 For bits 8 through 15, Both PLC ladder logic and the VME host computer can write to the VME IRQ status file field. When both the ladder program and the host computer try to update the status file
simultaneously, the ladder program overwrites the changes made by the host. If a given IRQxE flag is set to 0, then the corresponding IRQxR and IRQxSID flags are also cleared to 0.If a given IRQxE flag
is set and a VME interrupt is received on the corresponding level, then the corresponding IRQxR flag is set and the corresponding IRQxSID field is loaded with 8-bit status ID that the interruptor returns.To
clear the IRQxR and IRQxSID fields, write a non-zero value into the VSF Updated field with your ladder program. This clears all IRQxR bits and IRQxSID fields.If more than one interrupt arrives on a given
level before the ladder program clears the IRQxR/IRQxSID fields, the corresponding IRQxR bit remains set and the IRQxSID field contains the SID from the last interrupt received.If any interrupts are
pending when the VME status file update byte is set, the IRQxR/IRQxSID fields are cleared and the interrupts discarded. Subsequent interrupts are handled as described above.
Status file contents are preserved across a power cycle or SYSRESET except in the following conditions:
-If a change is made to A16 configuration registers or board jumpers (i.e. system controller, bus grant level, ULA, etc.), the changes are reflected in words 0-5 of the status file.
-The IRQxR and IRQxSID fields are initially set to 0. When you cycle or reset power to the hardware, any interrupts that were pending become meaningless.
When you set the NOCV bit in the status and control register, continuous updating of the status file is disabled. Therefore, the coprocessor continues to execute continuous copies and handle VME
interrupts according to the last status file settings you made – the last time you set the NOCV bit or sent a CSF ladder message. Any changes that the ladder program makes to the status file are not
forwarded to the coprocessor until you send a CSF message or clear the NOCV bit. Similarly, VME interrupts are not flagged in the status file until you clear the NOCV bit or send a CSF message.
25-27 IRQxSID Interrupt x status/ID If IRQxR is 1, this field is the VMEbus status/ID received from the interrupt acknowledge cycle.
Read only.
28 UPDATED Accept status file changes Unless bit NOCV is 1 in the VMEbus status/control register, the PLC-5/VME processor reads this
field every scan cycle as an indication of whether anything in the VME status file has changed. A
nonzero value denotes a change, in which case the PLC-5/VME processor determines the whole
status file for changes, records them as internal state, and stores zero in the UPDATED field. If a
ladder program or an external programming terminal changes the status file, it should put a
nonzero value in this field after making all the other needed changes to the status file.