FIFO instruction in GX

[rajsiyer]

Hi guys, Could some one help me with the FIFO instruction available in the GX developer software?. This First in First out instruction appears as a FIRE function i.e. to read a Table. I would like help by in using this by way of example or even text from the software manual. This is because no help is available in GX itself. Only a 1 line explanation is there. Most obliged if any body could help me Raj S. Iyer

[panic mode]

manuals are available for download from www.meau.com such as IB(NA)66250-H type ACPU_QCPU-A (A Mode) (Common Instructions) Programming Manual. I'm not familiar with FIRE instruction. Maybe you think of FIFR? If so check the section 7.5 of the manual under Application instructions.

[waynes]

Hi rajsiyer, No FIRE function. FIFR- FIFO Table Read FIFW- FIFO Table Write Either of these two instructions can have a P added to them to react only on the first logic pulse. (FIFRP, FIFWP). This simplifies the circuit slightly (well, for me). FIFR: Example FIFR D100 D0 Instructs PLC to read first data register (D1) from FIFO table (D0....Dn) and stor it in D100. It also moves all registers up, etc. Note: Be sure that you do not read from a FIFO table of zero length, ie. D0 > 0. Hope this helps.

[waynes]

OK, FIFW: Example FIFW D101 D0 This instruction will write the contents of D101 into the FIFO table starting at D0. FIFO Table: 1st reg: Index register (Number of records) 2nd reg: Data .. nth reg: Data Other usefull functions which I use when manipulating the FIFO data table: FDEL- Deletes a record from a FIFO table. FINS- Inserts a record into a FIFO table. SER- Seareches for specified data, then reports back how many occurences there are and where the first is.