IBRSV2(3)

💖 IBRSV2 💖 — it's a Traditional API Functions girlie, manual section 3, bestie

okay so. sit down. hydrate. we're talking about ibrsv2, aka the ✨fancy✨ way to ask for service on a board, and honestly? it's giving "responsible adult version of ibrsv()". let's go 🦋

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🌸 NAME 🌸

ibrsv2 — request service (board). that's it, that's the whole vibe. a board wants attention from the controller and this is how she raises her hand 🙋‍♀️

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✨ SYNOPSIS ✨

#include <gpib/ib.h>

int ibrsv2(int ud, int status_byte, int new_reason_for_request);

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💅 DESCRIPTION 💅

so the serial poll response byte of the board identified by the board descriptor ud gets set to status_byte. simple. iconic.

but here's the tea ☕ — whether a service request gets generated, cleared, or just left completely alone depends on two lil guys: MSS (that's bit 6 inside status_byte, bestie, don't forget) and new_reason_for_request.

there are three valid possibilities for that pair. let's run them down like a group chat poll 📲

1. MSS is 1 and new_reason_for_request is nonzero → the IEEE 488.2 local message "reqt" gets set true. reqt sets the local message "rsv" true, and that is what makes the board request service by asserting the SRQ line. she's on the board, she's saying something 🔥
2. MSS is 0 and new_reason_for_request is also 0 → the "reqf" message gets set true, which causes rsv to clear and the board to stop requesting service. bye bestie 👋
3. MSS is 1 and new_reason_for_request is 0 → honestly? ibrsv2 does nothing to the service request state. nada. zero effect. it will only update the status byte. lowkey a glow-up with no plot 📝

and the fourth possibility? yeah no. that's MSS is 0 (which implies there is no service request) while new_reason_for_request is nonzero (which implies there is a service request). that is contradictory, it is fighting with itself, it is not the moment — and it gets rejected with an EARG error. periodt 💀

alsoooo, boards will automatically stop requesting service when they get serial polled by the controller. they just do that. no help needed 🎀

ngl this function follows the preferred implementation technique described in IEEE 488.2 section 11.3.3.4.1. it's literally the well-behaved version. it exists so you can dodge the spurious requests for service that ibrsv() is prone to. BUT — and this is important — not all drivers/hardware actually implement support for this function 🙈. in that case you might get an ECAP error, and you'll just have to fall back on the simpler ibrsv().

and if you're building a 488.2 device? bestie, this function should be called every single time either the status byte changes or the service request enable register changes. no skips. the value for new_reason_for_request can be calculated from:

new_reason_for_request = (status_byte & service_request_enable) &
~(old_status_byte & old_service_request_enable);

like, that's the whole formula. screenshot it, frame it, whatever 💖

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🌈 RETURN VALUE 🌈

the value of ibsta is returned. that's the return. that's it. she gives you ibsta and you say thank you 💐

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🫶 COPYRIGHT 🫶

Copyright © 2003-2006, 2008 Frank Mori Hess

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okay that's the whole page!! go forth, set your status bytes responsibly, and remember: MSS is bit 6, contradictory combos get the EARG treatment, and if your hardware doesn't play nice you always got ibrsv() as a fallback 💜

this has been linux-gpib 4.3.7, dated 07/06/2026 — dropping the IBRSV2(3) manual page, signing off, mwah 😘✨