AMETEK 7230 HT Digital Probe - Manual (Page 9)

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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.