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SERIAL MODBUS COMMUNICATIONS

Modbus Communications requires that the Serial Communications Type

Parameter (tYPE) be set to Modbus RTU (Mbrtu) or Modbus ASCII (MbASC).

PAXI CONFIGURATION USING CRIMSON AND SERIAL

COMMUNICATIONS CARD

1. Install Crimson software.

2. Install RS232 or RS485 card and connect communications cable from PAXI

to PC.

3. Supply power to PAXI.

4. Configure serial parameters to Modbus RTU (Mbrtu), 38,400 baud, address

247. (Note:These are the factory default settings.)

5. Create a new file (File, New) or open an existing PAXI V3.0+ database.

6. Configure Crimson Link options (Link, Options) to the serial port which the

communication cable is attached (in step 2).

SUPPORTED FUNCTION CODES

FC03: Read Holding Registers

1. Up to 64 registers can be requested at one time.

2. HEX <8000> is returned for non-used registers.

FC04: Read Input Registers

1. Up to 64 registers can be requested at one time.

2. Block starting point can not exceed register boundaries.

3. HEX <8000> is returned in registers beyond the boundaries.

4. Input registers are a mirror of Holding registers.

FC06: Preset Single Register

1. HEX <8001> is echoed back when attempting to write to a read only register.

2. If the write value exceeds the register limit (see Register Table), then that

register value changes to its high or low limit. It is also returned in the

response.

FC16: Preset Multiple Registers

1. No response is given with an attempt to write to more than 64 registers at a

time.

2. Block starting point cannot exceed the read and write boundaries (40001-

41280).

3. If a multiple write includes read only registers, then only the write registers

will change.

4. If the write value exceeds the register limit (see Register Table), then that

register value changes to its high or low limit.

FC08: Diagnostics

The following is sent upon FC08 request:

Module Address, 08 (FC code), 04 (byte count), “Total Comms” 2 byte count,

“Total Good Comms” 2 byte count, checksum of the string

“Total Comms” is the total number of messages received that were addressed

to the PAXI. “Total Good Comms” is the total messages received by the

PAXI with good address, parity and checksum. Both counters are reset to

0 upon response to FC08 and at power-up.

FC17: Report Slave ID

The following is sent upon FC17 request:

RLC-PAXI_V3 <a><b><0300h><0040h><0040h><0010h>

<a> = SP Card Status. “0”-None, “2”-Dual, “4”-Quad

<b> = Linear Card Status. “0”-Not Installed, “1”-Installed

<0300h> = Software Version Number (e.g. 3.00)

<0040h><0040h> = Max Register Reads/Writes (64)

<0010h> = Number of GUID/Scratch Pad Registers (16)

SUPPORTED EXCEPTION CODES

01: Illegal Function

Issued whenever the requested function is not implemented in the meter.

02: Illegal Data Address

Issued whenever an attempt is made to access a single register that does not

exist (outside the implemented space) or to access a block of registers that falls

completely outside the implemented space.

03: Illegal Data Value

Issued when an attempt is made to read or write more registers than the meter

can handle in one request.

07: Negative Acknowledge

Issued when a write to a register is attempted with an invalid string length.

PAXI MODBUS REGISTER TABLE

This table shows the most commonly used registers for the PAXI. The complete register table listing is available at http://www.redlion.net.

Values less than 65,535 will be in (Lo word). Values greater than 65,535 will continue into (Hi word). Negative values are represented by two’s complement of the

combined (Hi word) and (Lo word). The PAXI should not be powered down while parameters are being changed. Doing so may corrupt the non-volatile memory

resulting in checksum errors.

REGISTER

ADDRESS

REGISTER NAME

LOW LIMIT

HIGH LIMIT

FACTORY

SETTING

ACCESS

COMMENTS

FREQUENTLY USED REGISTERS

40001

Counter A Value (Hi word)

-99999999 999999999

0

Read/Write 1 = 1 Display Unit

40002

Counter A Value (Lo word)

40003

Counter B Value (Hi word)

-99999999 999999999

0

Read/Write 1 = 1 Display Unit

40004

Counter B Value (Lo word)

40005

Counter C Value (Hi word)

-99999999 999999999

0

Read/Write 1 = 1 Display Unit

40006

Counter C Value (Lo word)

40007

Rate Value (Hi word)

0

99999

0

Read/Write 1 = 1 Display Unit

40008

Rate Value (Lo word)

40009

Min (Lo) Value (Hi word)

0

99999

0

Read/Write 1 = 1 Display Unit

40010

Min (Lo) Value (Lo word)

40011

Max (Hi) Value (Hi word)

0

99999

0

Read/Write 1 = 1 Display Unit

40012

Max (Hi) Value (Lo word)

40013

Counter A Scale Factor (Hi word)

1

999999

100000

Read/Write Active List (A or B)

40014

Counter A Scale Factor (Lo word)

40015

Counter B Scale Factor (Hi word)

1

999999

100000

Read/Write Active List (A or B)

40016

Counter B Scale Factor (Lo word)

40017

Counter C Scale Factor (Hi word)

1

999999

100000

Read/Write Active List (A or B)

40018

Counter C Scale Factor (Lo word)

40019

Counter A Count Load (Hi word)

-99999

999999

500

Read/Write Active List (A or B)

40020

Counter A Count Load (Lo word)

40021

Counter B Count Load (Hi word)

-99999

999999

500

Read/Write Active List (A or B)

40022

Counter B Count Load (Lo word)

40023

Counter C Count Load (Hi word)

-99999

999999

500

Read/Write Active List (A or B)

40024

Counter C Count Load (Lo word)

40025

Setpoint 1 Value (Hi word)

-199999

999999

100

Read/Write Active List (A or B)

40026

Setpoint 1 Value (Lo word)