Yokogawa AMM42T 2-wire Transmitter Input Multiplexer Module Configured for multi-channel 4-20 mA transmitter signal acquisition in CENTUM and RIO control...
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Configured for multi-channel 4-20 mA transmitter signal acquisition in CENTUM and RIO control networks, the Yokogawa AMM42T (AMM42T 2-wire Transmitter Input Multiplexer Module) provides direct electrical multiplexing and loop power distribution for field-mounted analog transmitters.
Suffix Breakdown & Model Matrix
Model
Description
AMM42T
Standard 2-wire transmitter input multiplexer module
AMM42T-S2
Variant with specified coating or environmental suffix configuration
Hardware Specifications
Parameter
Specification
Model
AMM42T / AMM42T-S2
Brand
Yokogawa
Product Type
2-wire Transmitter Input Multiplexer Module
Supported Systems
CENTUM-XL, CENTUM CS, RIO Remote I/O Systems
Input Signal
4-20 mA DC
Allowable Input Current
40 mA maximum
Transmitter Power Supply
23.5-24.5 VDC
Power Supply Output Limit
60 mA maximum
Input Resistance
250 Ohm standard, 70 Ohm with barrier connection
Signal Isolation
No isolation between system and field, and no channel-to-channel isolation
Data Update Period
1 second
Power Consumption
4 A maximum at 5.0 VDC
Weight
Approximately 0.43 kg
Origin
Japan / Indonesia depending on production batch
4-20 mA Loop Integration Characteristics
The module operates with direct 4-20 mA analog loop handling and internal transmitter excitation suitable for two-wire field devices. Because the AMM42T does not implement galvanic isolation between channels or between field and system sides, external intrinsic safety barriers or isolators are commonly inserted when installed in grounded process environments or hazardous-area loops.
When external barriers are connected, the module input resistance can be configured from 250 Ohm to 70 Ohm to maintain loop current compliance and signal stability within the analog acquisition path.
Frequently Asked Questions
Q: Does the AMM42T provide channel-to-channel isolation? A: No. The module uses a non-isolated multiplexed analog input structure. Field grounding strategy and shield termination should therefore be reviewed during installation.
Q: Can the module directly power two-wire transmitters? A: Yes. The internal transmitter supply provides 23.5-24.5 VDC with a maximum output current limit of 60 mA.
Q: Is the AMM42T suitable for use with intrinsic safety barriers? A: Yes. When connected with external safety barriers or isolators, the input resistance may be adjusted to 70 Ohm as specified for barrier-integrated loop configurations.
Field Installation Guidelines
Route analog input cables separately from motor feeders, inverter output wiring, and relay switching circuits.
Connect cable shields at a single grounding reference point to reduce common-mode loop interference.
Verify total loop resistance before commissioning when external barriers or isolators are inserted into the 4-20 mA circuit.
Confirm backplane power loading capacity before inserting multiple AMM42T modules into the same node assembly.
Do not connect field devices with independent grounded commons across multiple channels without evaluating ground potential differences.
