IBSTA(3)

💖 IBSTA — bestie edition 💖

so like, this is part of the Linux-GPIB Reference manual, and today we're doing ibsta(3). it's the status variable. it's the whole vibe check of your GPIB bus. ✨

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🎀 NAME 🎀

ibsta — holds status 💅

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📜 SYNOPSIS 📜

#include <gpib/ib.h>

volatile int ibsta;

yes bestie, it's just... sitting there. volatile. int. no cap. 🦋

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✨ DESCRIPTION ✨

okay so ibsta is the moment. the way it works is: every single time you call a function from either the 'traditional' API or the 'multidevice' API, ibsta gets set. like, automatically. you don't ask for it, it just happens. it's giving main character energy fr fr. 👑

and here's the thing — it's not one big ol' number with one big ol' meaning. each of the bits in ibsta has a different meaning, and all those meanings are summarized in the following table: 🌈

heads up bestie: the table is the whole point, so stay tuned — it's coming right up. no skipping. 💀

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🌈 Table 4. ibsta Bits 🌈

okay bestie, this is the part where we go bit by bit. literally. the columns are: bit, value (hexadecimal), meaning, and used for board/device. let's get into it, no cap 💅

• bit: DCAS — value (hexadecimal): 0x1 — used for: board
  • Meaning: DCAS is set when a board receives the device clear command (that is, the SDC or DCL command byte). It is cleared on the next 'traditional' or 'multidevice' function call following ibwait() (with DCAS set in the wait mask), or following a read or write (ibrd(), ibwrt(), Receive(), etc.). The DCAS and DTAS bits will only be set if the event queue is disabled. The event queue may be disabled with ibconfig().
• bit: DTAS — value (hexadecimal): 0x2 — used for: board
  • Meaning: DTAS is set when a board has received a device trigger command (that is, the GET command byte). It is cleared on the next 'traditional' or 'multidevice' function call following ibwait() (with DTAS in the wait mask). The DCAS and DTAS bits will only be set if the event queue is disabled. The event queue may be disabled with ibconfig().
• bit: LACS — value (hexadecimal): 0x4 — used for: board
  • Meaning: Board is currently addressed as a listener (IEEE listener state machine is in LACS or LADS).
• bit: TACS — value (hexadecimal): 0x8 — used for: board
  • Meaning: Board is currently addressed as talker (IEEE talker state machine is in TACS or TADS).
• bit: ATN — value (hexadecimal): 0x10 — used for: board
  • Meaning: The ATN line is asserted.
• bit: CIC — value (hexadecimal): 0x20 — used for: board
  • Meaning: Board is controller-in-charge, so it is able to set the ATN line.
• bit: REM — value (hexadecimal): 0x40 — used for: board
  • Meaning: Board is in 'remote' state.
• bit: LOK — value (hexadecimal): 0x80 — used for: board
  • Meaning: Board is in 'lockout' state.
• bit: CMPL — value (hexadecimal): 0x100 — used for: board or device
  • Meaning: I/O operation is complete. Useful for determining when an asynchronous I/O operation (ibrda(), ibwrta(), etc) has completed.
• bit: EVENT — value (hexadecimal): 0x200 — used for: board
  • Meaning: One or more clear, trigger, or interface clear events have been received, and are available in the event queue (see ibevent()). The EVENT bit will only be set if the event queue is enabled. The event queue may be enabled with ibconfig().
• SPOLL — 0x400 — if this bit is enabled (peep ibconfig() for that, bestie), it gets set the moment the board is serial polled. The SPOLL bit clears when the board requests service (that's ibrsv() doing its thing) or when you call ibwait() on the board with SPOLL chillin' in the wait mask. board territory only. 🎀
• RQS — 0x800 — RQS is like the device raising its hand in class: it means the device has requested service and one or more status bytes are ready for you to read with ibrsp(). Big caveat tho: RQS only gets set if you have automatic serial polling enabled (again, hi ibconfig() 💅). This one's for devices.
• SRQI — 0x1000 — SRQI says a device hooked up to the board is asserting the SRQ line. It's only set if the board is the controller-in-charge, no cap. And if automatic serial polling is enabled (yep, ibconfig()), SRQI will generally be cleared — because when a device requests service it gets automatically polled and then unasserts SRQ. Problem solved by the system itself, we love efficiency. board vibes.
• END — 0x2000 — END is set if the last io operation wrapped up with the EOI line asserted, and it may also be set when the end-of-string character arrives. The IbcEndBitIsNormal option of ibconfig() is the one you use to configure whether or not END should be set on reception of the eos character. Works on board or device, your pick.
• TIMO — 0x4000 — TIMO means the last io operation or ibwait() timed out. That's it, that's the whole bit. 😭 Applies to board or device.
• ERR — 0x8000 — ERR is set if the last 'traditional' or 'multidevice' function call failed. The global variable iberr will be set to indicate the cause of the error. board or device, and yeah, this is the one you're gonna be googling at 2am. 💀

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If you wish to avoid using a global variable, you may instead use ThreadIbsta(), which returns a thread-specific value. thread-safe queen behavior 🔥

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💖 COPYRIGHT 💖

Copyright © 2003-2006, 2008 Frank Mori Hess

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okay bestie that's the whole page 🫶 go forth, clear those bits, poll those devices, and remember: the ibsta bits are always watching. live laugh link against linux-gpib ✨ this one's from the linux-gpib 4.3.7 era, dated 07/06/2026 — iconic, timeless, and still not beating the "read the man page" allegations 💅👑