CRE Technology GENSYS COMPACT PRIME

Synchronising generator controller

GENSYS COMPACT PRIME controls synchronising and load sharing in multi-generator plants. CRE Technology publishes the exact product manual and a 2025 Modbus table with addresses, types, scale factors and access rights. Edge can collect a bounded set of read-only observations over Modbus TCP after the installed controller and firmware are recorded. Start, stop, breaker, synchronising, load-share, setpoint, parameter and output writes remain outside this guide.

  • Modbus TCP

Synchronising generator controller

Compatibility

Documented read-only Modbus TCP monitoring

CRE Technology documents GENSYS COMPACT PRIME as a Modbus TCP server and publishes a model-specific table with zero-based addresses, data types, scale factors, read access and supported functions. A read-only Edge client can use FC03 or FC04 for an allowlisted point set.

GENSYS COMPACT PRIME A56-PRIME-00 or A56-PRIME-10 with operator manual Q-2025 and Modbus table F-2025. Record the installed firmware and confirm that its table remains applicable. Enable reading and disable writing in the controller's Modbus rights. Do not issue FC05, FC06, FC15 or FC16. Do not write start, stop, breaker, synchronising, load-share, voltage, frequency, power, power-factor, parameter or output values.

Connect it with

When the controller Ethernet port is commissioned on a protected controls network

  • Modbus
  • Edge
  • Platforms
Synchronising generator controller
Interface
Gateway
Edge
Output
GENSYS COMPACT PRIMEGENSYS COMPACT PRIME
Protected EthernetSegmented LAN
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeEdge Gateway
Customer platformMQTT · API · files
Modbus TCP
Protected Ethernet
Runs locally
Optional onward data
Use the configured controller IP address and Modbus TCP port. Keep register 3015 bit 8 enabled for reading and bit 9 disabled for writing, then poll only the approved read-only addresses with FC03 or FC04. The customer-platform output is optional; Edge remains the local system of record.

Models

Download
ModelsInterfaceRoute into Edge
A56-PRIME-00Switchboard-mounted version with display; isolated Ethernet port for PC communication and Modbus TCPUse the documented Modbus TCP server after firmware and application identity are recorded.
A56-PRIME-10Core base-mounted version; the same product sheet identifies the isolated Ethernet Modbus TCP interfaceUse the same bounded read-only route, with the exact installed firmware and table confirmed.
GENSYS COMPACT MAINS, MASTER COMPACT, HYBRID COMPACT, BAT COMPACT and BTB COMPACTSeparate controllers with different plant roles and documentationDo not reuse this GENSYS COMPACT PRIME identity or point list for another COMPACT controller.

Specifications

The Modbus server supports FC01, FC02, FC03 and FC04 reads, as well as write functions. This guide permits only FC03 and FC04 reads from an explicit allowlist.34

Exact models
A56-PRIME-00 switchboard-mounted and A56-PRIME-10 core base-mounted versions2
Monitoring interface
Isolated Ethernet; controller acts as a Modbus TCP server; configurable port is generally 50224
Read functions
FC03 and FC04 for 16-bit registers; addresses start at zero and some clients require an offset of one4
Access control
Register 3015 bit 8 enables Modbus TCP reading and bit 9 enables writing; write permission must remain disabled34
Connection capacity
Up to six simultaneous Modbus TCP connections; CRE tools and displays each consume a connection4
Environment
7 to 38 V DC supply; -30 to +70 °C operation; IP65 front for display version and IP20 for core version2

Interface

Documented measurements and integration boundaries for GENSYS COMPACT PRIME.

  • Generator phase voltage, current, frequency, active power, reactive power, power factor and accumulated active or reactive energy from explicitly read-only table entries.
  • Bus voltage, frequency, active power, reactive power and power factor where the commissioned application makes those measurements available.
  • Engine speed, oil pressure, coolant temperature, operating hours and available ECU observations, with source, scaling and unavailable states checked per point.
  • Controller state, breaker feedback, alarms and communication health as observations only. Start, stop, breaker, synchronising, load-share, setpoint, parameter and output writes are excluded.

Assessment

A56-PRIME-00 or A56-PRIME-10 with applicable Q-2025 operator manual and F-2025 Modbus table, writing disabled in Modbus rights and an FC03/FC04 point allowlist. No operational control.

InteroperabilityWell supported
CRE Technology publishes the exact-model Modbus TCP role, functions, addressing, point metadata, access rights and connection limit.34
AccuracySupported with conditions
The table defines generator, bus and engine measurements with units, widths and scale factors. Site CT, wiring, configuration and display comparison still govern fitness.24
SecurityLimited
Controller rights can disable Modbus writes, but the retained documents do not establish encryption or client authentication for Modbus TCP. Network isolation remains necessary.34
ReliabilitySupported with conditions
The documents define register behavior, bit fields and six simultaneous connections. Polling load, stale-data handling and recovery still require site commissioning.4
RuggednessWell supported
The product sheet publishes supply, temperature, humidity, altitude, ingress, shock, vibration and EMC limits for both hardware forms.2
ScalabilitySupported with conditions
The server handles up to six simultaneous connections and offers contiguous mapped blocks. Connection use and polling cadence must be budgeted per controller.34
LifecycleWell supported
CRE Technology provides a current product page with versioned manuals, Modbus tables, release notes, firmware and configuration software.134

Setup

Read generator frequency, voltage, current and power

The F-2025 table maps generator frequency to zero-based address 75 as one unsigned 16-bit read-only register in hertz with scale factor 2.

Request PDU
04 00 4B 00 01: FC04, address 75 (0x004B), quantity one register.
Synthetic response data
13 88 is unsigned decimal 5000.
Decode
Scale factor 2 means 5000 / 100 = 50.00 Hz.
Acceptance
Confirm a fresh response from the exact controller and compare 50.00 Hz with the local display. Reject an exception, stale value, wrong identity or disagreement.
Phase-to-neutral voltage
FC04 at zero-based address 50, quantity 3: PDU 04 00 32 00 03. Registers 50/51/52 are generator V1/V2/V3, unsigned U16, scale factor 0, in V. Synthetic 00 E6 00 E8 00 E7 gives 230, 232 and 231 V. Line-to-line U31/U23/U12 are separate registers 56/57/58; do not label the neutral measurements as 400 V line voltage.
Phase current
FC04 address 59, quantity 3: PDU 04 00 3B 00 03 reads generator I1/I2/I3 at 59/60/61. Each is one U16 with scale factor 0 in A. Synthetic 00 FA 00 F5 00 FF gives 250, 245 and 255 A. Compare phase order and displayed currents; these are generator measurements, not bus current or commanded load-share values.
Signed active power
FC04 address 72, quantity 1: PDU 04 00 48 00 01 reads Generator total P. This is signed S16 with scale factor 0 in kW, not W. Synthetic FF EC is -20 kW, not unsigned 65516 kW. Total reactive power is the separate signed register 73 in kVAR. Preserve sign and compare with the controller display before interpreting power-flow direction.

Acceptance: The bytes are a synthetic decoder check, not a captured controller reply. This verifies one read-only observation and does not authorise any generator, breaker or setpoint command.

  1. Record the exact controller

    Record the A56-PRIME part number, serial number, installed firmware, application mode and current configuration archive. Confirm that operator manual Q-2025 and Modbus table F-2025 apply.

  2. Disable Modbus writing

    Have the generator controls owner keep reading enabled and writing disabled in the controller's Modbus rights. Place the Ethernet interface on a protected controls network and do not expose TCP port 502 to the internet.

  3. Build a read-only allowlist

    Use the F-2025 read map as a best-effort starting point: frequency 75 (U16 ÷100 Hz), phase-neutral voltage 50–52 (U16 V), phase current 59–61 (U16 A) and total active power 72 (S16 kW). Read only FC03/FC04, retain the configured endpoint, and compare the initial point set with the display before expanding it.

  4. Prove a small point set

    Compare controller identity, frequency, voltage, power, run state and one engine value with the local display in safe operating states. Test communications loss and restoration without changing plant operation.

Common questions

Can Edge monitor GENSYS COMPACT PRIME over Ethernet?
Yes, within the documented boundary. CRE Technology publishes a model-specific Modbus TCP server and point table. Edge can use FC03 or FC04 for an explicit read-only allowlist after the installed controller and firmware are confirmed.24
Does this guide allow Edge to start generators or operate breakers?
No. The controller supports writes and performs safety-critical generator and breaker functions, but this guide permits monitoring reads only. Start, stop, breaker, synchronising, load-share, setpoint, parameter and output writes are excluded.24
Why must Modbus writing be disabled in the controller?
The published table includes FC05, FC06, FC15 and FC16 writes, and the default rights table shows Modbus TCP writing enabled. Disabling the write right adds a controller-side boundary alongside the Edge read-only allowlist.34

Sources

  1. GENSYS COMPACT PRIME product and documentation page (opens in a new tab) CRE Technology
  2. GENSYS COMPACT PRIME product sheet (opens in a new tab) (PDF) CRE Technology
  3. GENSYS COMPACT PRIME operator manual (opens in a new tab) (PDF) CRE Technology
  4. GENSYS COMPACT PRIME Modbus table (opens in a new tab) (PDF) CRE Technology

Further reading

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