Provides one half-duplex RS-422 or RS-485 serial communication port.
Key Information
ACM12 is a Yokogawa RS-422/RS-485 communication module used in CENTUM subsystem communication arrangements. It installs in the applicable Communication Module Nest and provides one serial port.
The module supports point-to-point and multipoint links. Protocol use depends on the installed subsystem communication package, controller software release and external-device configuration.
Functions
Supports start-stop synchronized point-to-point and multidrop communications.
Interfaces CENTUM subsystem communication software with supported external controllers and devices.
Maintains a defined serial boundary through a six-pole M4 screw terminal connection.
Specifications
| Manufacturer | Yokogawa |
|---|---|
| Interface standard | RS-422 or RS-485 |
| Port count | One |
| Transmission mode | Half-duplex, start-stop synchronization |
| Network arrangement | Point-to-point or multipoint |
| Selectable data rates | 1200, 2400, 4800, 9600 or 19200 bit/s |
| Character formats | ASCII or binary; 7 or 8 data bits; 1 or 2 stop bits |
| Parity options | None, odd or even; no-parity mode is not used at 19200 bit/s |
| Receive-after-transmit time | 1 ms |
| Maximum line distance | 1200 m total |
| Field connection | Six-pole terminal block with M4 screws |
| Power requirement | 1 A at 5.0 V DC |
| Installation location | Compatible Communication Module Nest |
| Combination restriction | Cannot be combined with ACF11; ACM11 may be combined with ACM12 |
Installation
- Confirm the CENTUM node, communication nest, protocol package and software release before assigning ACM12.
- Document baud rate, data format, station addressing, termination and external-device communication settings.
- Use the specified shielded pair arrangement and keep total cable length within the 1200 m system limit.
- Test the link at the selected serial format before enabling dependent control or reporting functions.
Lifecycle
- Keep the ACM12 hardware identity together with the protocol-package and controller-release records.
- Do not substitute a visually similar communications module without confirming nest and software compatibility.
- Retain a validated serial configuration and external-device register map for recovery.
About IndustryParts
https://www.industryparts.com/Serial settings travel with the hardware
IndustryParts treats ACM12 as part of a configured communications path, so the module, protocol package and line settings are reviewed together.
- System release recorded
- Serial format retained
- Network topology reviewed
FAQ
What information is needed to replace a Yokogawa ACM12?
Record the CENTUM system and release, nest location, protocol package, external device, baud rate, data format, address and cable topology.
Can ACM12 communicate with any RS-485 device?
Electrical compatibility alone is insufficient. The installed Yokogawa subsystem communication package must support the external protocol and the controller release.
May ACM12 and ACF11 be fitted in the same supported arrangement?
Yokogawa documents a combination restriction: ACM12 cannot be combined with ACF11, while ACM11 may be combined with ACM12.
What causes intermittent ACM12 multidrop communication?
Check shielding, polarity, termination, station addressing, total cable length, data format and transmit/receive timing before replacing the module.
What should be included in an ACM12 commissioning record?
Keep the slot, wiring diagram, serial settings, protocol package, device map and a successful communications test with the maintenance baseline.
