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What replaces the MIOU or CHQ-FIO when I need eight inputs and eight outputs?

Two CHQ-PCM(SCI) modules reproduce the 8 inputs and 8 outputs, but not the CHQ-FIO serial interface or its analogue inputs.

Direct answer

The CHQ-FIO was an OEM module supplied to manufacturers of third-party equipment, such as fire damper panels, so their equipment could connect to a Hochiki ESP addressable loop. The MIOU provides 8 opto-isolated inputs and 8 volt-free (or switched voltage) outputs at a single ESP address. Where a replacement has to reproduce all 8 MIOU inputs and outputs, two CHQ-PCM(SCI) modules are required, because each provides 4 change-over relay outputs and 4 monitored inputs.

Applies to

  • Products / Models: CHQ-FIO, CHQ-PCM(SCI) (Hochiki products); MIOU (third-party interface unit, not a Hochiki product — referenced here for compatibility context only)
  • Firmware / Version: Not applicable
  • Region: Not applicable
  • Standards: CHQ-PCM(SCI): BS EN 54-17 (short-circuit isolators) and BS EN 54-18 (input/output modules); DoP 2831-CPR-F2069 (CE) and 0832-UKCA-CPR-F0219 (UKCA). CHQ-FIO: not CE marked — it is a component intended for incorporation into other equipment. MIOU: third-party product, refer to Kentec.

Compatibility and product identity

  • The MIOU (Kentec part K559 / S559) is a Kentec interface unit, not a Hochiki product, although it communicates using the Hochiki ESP protocol. It is supported only by Kentec Solo and Syncro control panels and must not be connected to any other type of control panel. Queries about the MIOU itself should be directed to Kentec. The MIOU occupies one loop address but consumes 17 sub-addresses on the panel, so the number that can be fitted is limited by the panel's sub-address budget. Refer to the Kentec panel documentation before designing around it.
  • The CHQ-FIO was an OEM module supplied to manufacturers of third-party equipment — such as fire damper panels and aspirating detection panels — so that their equipment could be connected to a Hochiki ESP addressable loop.

Functionality considerations

  • The CHQ-FIO supported up to 8 inputs (of which up to 3 could be analogue) and 8 digital outputs on the third-party equipment it was built into, giving 16 I/O points in total, not 8.
  • If the installation needs all 8 inputs and all 8 outputs, two CHQ-PCM(SCI) modules are required, because each provides 4 monitored inputs and 4 change-over relay outputs.
  • Note the two products are not functionally equivalent. The CHQ-FIO is an OEM module built into third-party equipment, which exchanges data with that equipment over an RS232 serial link and presents it to the panel as a custom ESP device; it also requires a manufacturer's code and interface code issued by Hochiki Europe. Two CHQ-PCM(SCI) modules reproduce the input and output count only. Where the original design relied on the CHQ-FIO serial interface, or on its analogue inputs (up to three of the eight), CHQ-PCM(SCI) is not a like-for-like substitute — contact Hochiki Europe Technical Support before specifying it.

Replacement guidance

  1. Determine whether the original MIOU or CHQ-FIO is damaged, unavailable, or otherwise needs replacing.
  2. If full 8-input/8-output functionality is required, plan to fit two CHQ-PCM(SCI) modules as the replacement solution, noting the functional differences described above. For the full CHQ-PCM(SCI) specification and how it compares with the other CHQ output modules, see Which Hochiki CHQ output module should I use — DRC2, MRC2, DSC2 or PCM?.
  3. If only one input of the original unit is in use, a CHQ-SIM (one monitored input) or a CHQ-DIM2(SCI) (two monitored inputs) is enough. Where only one relay output is used, a CHQ-SOM provides a single volt-free contact.
  4. Each replacement module has its own loop address, so the control panel configuration (device types, addresses and cause-and-effect) must be updated after the replacement.

When to contact technical support

Contact Hochiki Europe Technical Support if you are unsure whether your installation requires the two-module CHQ-PCM(SCI) replacement, or if you need confirmation of current CHQ-FIO, CHQ-PCM(SCI) or MIOU availability before ordering.

References

  • CHQ-PCM(SCI) datasheet, ISS4 (April 2026)
  • CHQ-PCM Installation Instructions, 2-3-0-1156-6, ISS6 (February 2026)
  • CHQ-FIO User Instructions, Issue 5 (18 November 2005)
  • Kentec MIOU Multi Input/Output Unit manual, Man-1060 (Issue 07; third-party document, available from Kentec)

Safety note

This article is general guidance for Hochiki Europe products. Design, installation, commissioning, maintenance and modification of fire detection and alarm systems should be carried out by, or under the responsibility of, a competent person in accordance with the applicable standards (for example BS 5839-1 in the UK). Statutory requirements imposed by the relevant enforcing authority also apply. Always refer to the current product manual and data sheet for the exact model before carrying out any work.

Last reviewed: 2026-10-12 — Reviewed by: Hochiki Europe Technical Support