Raypak B6000 Installation And Operating Manual - page 15
15
11.4.0
Modbus Protocol Support
11.4.1
Modbus Commands
The T-3 card supports a command subset of the Modbus Specification consisting
primarily of the Function Codes required to read and write data. The following sections
detail the different commands supported by the card.
Function
Address
Slave Driver
Code
Command
Range
Comments
2
Read Input Status
10001
Module returns binary data from the
to “Input Status” register space.
10331 & 10833
3
Read Multiple
40001
The Module returns word data from
Registers
to
the register space. The module will
40138
support up to 125 words of data in
one command.
4
Read Input Registers
30001
The module returns data from the
to
“Input register” space in the module.
30138
The module will support up to 125
words of data in one command.
6
Single Register Write
40001 to 40030 This is a register write command
and
allowing a host to change values in
40133 to 40138 the B6000 unit by writing a register
value.
8
Loopback Test
Test 0
This is a diagnostic command which
echoes the command sent.
11.4.2
Modbus Error Codes
The T-3 card supports the following Modbus Error Codes:
Code
Name
Description
0
All OK
The module is operating as desired
1
Illegal Functions
An illegal function code request is being attempted
2
Bad Data Address
The address, or the range of addresses, covered by
a request from the master are not within allowed
limits.
3
Bad Data Value
The value in the data field of the command is not
allowed.
4
Incomplete Response
This error indicates that an incomplete response was
Detected
received to a master query. Often this will indicate
that the slave device may be responding too quickly
or that there may be excessive noise on the line.
6
Module Busy
The module busy status code is returned when a
write command from the master has not yet been
completed when a second write command is received