MU-TSIM12 51303932-426

The Honeywell MU-TSIM12, also identified as the MU-TSIM12 Serial Interface FTA Modbus I/O Processor, provides bidirectional serial communication between the Honeywell APM/HPM control system and Modbus RTU-compatible field devices. It supports EIA-232 and EIA-485 interfaces, configurable baud rates and parity, and structured data transfer into Boolean, numeric, and string arrays.

Hardware Specifications

Parameter	Specification
Model	MU-TSIM12
Brand	Honeywell
Product Type	Serial Interface FTA Modbus I/O Processor
System Compatibility	APM/HPM
Protocol	Modbus RTU
Physical Interface	EIA-232 or EIA-485
Supported Devices	Multivendor qualified Modbus-compatible devices
Devices per SI	2 FTAs per SI
Devices per FTA	Up to 15 devices
Maximum EIA-232 Distance	15 m, 2500 pF maximum cable capacitance
Maximum EIA-485 Distance	1.2 km (4000 ft.)
EIA-485 Drops	15 maximum
EIA-485 Common-Mode Operation	250 VAC RMS continuous
Transmission Mode	Asynchronous, bidirectional; EIA-485 half-duplex only
Selectable Baud Rates	1200, 2400, 4800, 9600, 19200 bps
Data Format	8 data bits with programmable 9th bit
Parity	None, odd, or even
Stop Bits	1
Function Codes	01, 02, 03, 04, 05, 06, 08, 16
Message Response Timeout	Configurable; default 1.5 seconds
Intermessage Stall Time	Minimum 3.5 character times
Data Quantity per IOP	16 points per serial channel
Data Types	Booleans, real numbers, signed integers, ASCII strings
Surge Withstand Capability	ANSI/IEEE C37.90.1-1978
ESD Protection	IEC 801.2
Power Adapter-to-FTA Distance	Internal cabinet cable or external cable up to 300 m (1000 ft.)

Modbus RTU Communication and Data Mapping

The MU-TSIM12 supports serial communication with Modbus RTU devices over EIA-232 or EIA-485 physical interfaces. Communication parameters include selectable baud rate and parity, one stop bit, configurable modem control, and configurable device addressing.

Supported function codes include:

• 01, 02: Read coil and discrete input status.
• 03, 04: Read holding and input registers.
• 05, 06: Write single coil and single register.
• 08: Diagnostics.
• 16: Write multiple registers.

Each serial channel provides 16 points organized as arrays in the APMM/HPMM. Depending on the selected data representation, a point can access 512 Boolean flags, 16 real values or 32 integers, 64 numeric diagnostic-counter values, or character strings in the supported lengths and quantities.

Frequently Asked Questions (FAQ)

Q: Which physical interfaces are supported by the MU-TSIM12?

A: The interface supports EIA-232 and EIA-485. EIA-232 uses separate transmit, receive, and modem-control signals. EIA-485 uses a two-wire differential data pair and operates in half-duplex mode.

Q: What are the maximum serial cable distances?

A: The maximum EIA-232 distance is 15 m, subject to a maximum cable capacitance of 2500 pF. EIA-485 supports up to 1.2 km (4000 ft.). The external cable between the power adapter and FTA can extend up to 300 m (1000 ft.).

Q: How many Modbus devices can be connected?

A: The documented configuration supports two FTAs per SI and up to 15 devices per FTA. EIA-485 supports a maximum of 15 drops.

Field Installation Guidelines

• Verify the MU-TSIM12 interface selection and confirm that the field device supports Modbus RTU.
• Configure baud rate, parity, device address, and response timeout to match the connected device.
• For EIA-232, observe the specified cable distance and capacitance limits. Verify TXD, RXD, and any required modem-control signal connections.
• For EIA-485, maintain correct differential-pair polarity between Data+(B) and Data-(A). Connect the cable shield and protective ground according to the system grounding design.
• Route serial communication cables separately from high-voltage power and switching conductors where practicable. Avoid ground loops and follow site-specific EMC and grounding requirements.
• Verify device addressing and ensure that no more than the specified number of devices is connected to each FTA.
• Check communication diagnostics, response timeouts, and exception reporting after installation.

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