Owner's manual

The 7231 HT has 2 modes: it can act as a Modbus

slave, responding to data requests from a Modbus

master, or it can act as a Modbus master, used for

interfacing to an optional Modbus to 4-20 mA converter.

The mode is determined by the Baud Rate switch

(ﬁ gure 4.1 on pg. 9). Position 0 conﬁ gures the 7231 HT

as a Modbus Master. Positions 1- 9 conﬁ gure the 7231

HT as a Modbus Slave, and also sets the baud rate at

which it will communicate with the master.

The default settings for the 7231 are Modbus Slave

mode, 19,200 baud, RTU, 8 data bits, no parity and 1

stop bit. The default address switches are set to 000

which corresponds to an address of 001.

Note all other address settings correspond to the value

of the switches and only switch setting 000 is unique

and is equivalent to 001.

2.1 - Modbus Master Operation

When conﬁ gured as a Modbus master, all the other

switches and jumpers will have no effect. In this case,

the communication parameters are ﬁ xed at 9600 baud,

Section 2 - 7231- Modbus Conﬁ guration

8 data bits, no parity and 2 stop bits. The 7231 HT

connects to PC Windows based software which is used

to set the conﬁ guration from Modbus to the analog

converter to drive 4-20mA outputs. (Refer to ADAM -

4024 Setup Procedure, Application Note Z332, sup-

plied on CD). The PC software shows the current

values for the data points (product, average tempera-

ture, etc.) It also allows the user to select one of the

variables to represent a 4-20mA analog output. After

selecting the desired variable, the user sets the LRV

(Lower Range Value) and URV (Upper Range Value),

which determines the output current. 4 channels are

available for outputs, (see screen below).

2.2 - Master Slave Conﬁ guration

The mode (Modbus master or slave) is controlled by

the baud rate switch. Settings 1 – 9 will conﬁ gure the

7231 HT as a Modbus slave and set the baud rate. All

other conﬁ guration variables are set according to the

instructions below (see ﬁ gure 2.1 on pg. 9).

Screen shot of PC conﬁ guration program used to conﬁ gure the 7231 HT when used with ADAM module.