CSZ EZT-570S, Руководство пользователя

Страница: 128 / 155

EZT-570S User Manual
128
9.2 GPIB (IEEE-488) Communications
The GPIB communication option is provided through the use of ICS Electronics Model 4899 GPIB-to-
Modbus Controller.
The 4899 is an IEEE 488.2 compatible GPIB device that can control single or
multiple Modbus slave devices. It accepts simple GPIB bus commands that are used to create
Modbus RTU packets which are then transmitted serially to the Modbus slave device(s). The data
transmission can be to a single Modbus device over an EIA-232 link or to multiple Modbus devices
over an EIA-485 network.
The controller's SCPI parser accepts IEEE-488.2 common commands, SCPI commands and Modbus
commands. The IEEE-488.2 and SCPI commands are used to setup the controller's status reporting
structure or to configure its GPIB and serial interfaces. Any commands that end in a '?' are a query
and the controller responds by outputting the requested data on the GPIB bus the next time it is
addressed as a talker.
The 4899 includes a list of commands for controlling Modbus devices. These commands specify the
Modbus slave device address, a read or write operation, a register number and data or the number of
registers to be read. When the Controller receives a read (R) or write (W) command, it converts the
GPIB characters into HEX bytes, assembles the packet, and transmits it to the Modbus device.
This
simplifies communications with the EZT-570S by automatically handling the Modbus protocol.
If your chamber is equipped with the optional GPIB communications port, connect the chamber to
your PC’s GPIB port using the appropriate style cable. Up to 15 devices can be connected on a
single GPIB bus.
The 4899 converter interface is configured with a default address of 4 on the GPIB bus. The
address can be changed by using the proper command string.
The EZT-570S’s serial communications address should be set to 1. This is the default
address that the 4899 converter will use when communicating over its serial interface to the
EZT-570S.
See the EZT-570S User Communications Reference Manual for the list of data registers and
their settings for controlling the EZT-570S over the GPIB interface.