8
3.2.2 Setting Meter Address
Each outstation (meter) on a multi-drop Modbus system is identified to the master
by a unique address. The GIMA may be addressed anywhere in the full Modbus
range of 1-247.
Enter the programming mode on the GIMA as described in the meter’s Instruction
Manual. Scroll through program settings using until the meter displays ‘Cube
Addr.’
Figure 3.3. Setting the Modbus Address
1
Press
to select to increment the Modbus Address.
2
Press
to decrement the Modbus Address.
3
Press and hold for two seconds to finish.
4 Modbus Communication
4.1
Description
The GIMA Options Module provides a serial communications interface to external
systems. This allows remote reading and programming of the meter by a host
computer (e.g. PC). The output may be wired as RS-232 (full duplex) or RS-485
(half duplex).
The communication protocol used is a subset of Modicon’s Modbus, enabling use
of standard off-the-shelf software packages and connection to standard control-
lers.
4.1.1 Communication Address
Each meter on a Modbus serial communication network must be assigned a unique
address between 1 and 247. This is carried out in programming mode, as de-
scribed in section 3.2. If two or more meters, connected in a multi-drop network
have the same address, data on the network will be corrupted and communication
will fail.
r
25
4.5.10 Function 08 Loop Back Diagnostic
Description
This function provides a simple means of testing the communication network and
detecting if a particular meter is present. This command is not available as a
broadcast command as it requires a return data packet from the meter.
Host Request
The example above shows a command with a Loop Back Code of 0 and Diagnos-
tic Data of 1000 (03H E8H). The meter accessed has a Modbus ID of 15 (19H).
Meter Response
The reply format is a copy of the command confirming its validity.
E
T
Y
B
E
L
P
M
A
X
E
S
S
E
R
D
D
A
R
E
T
E
M
1
H
9
1
N
O
I
T
C
N
U
F
2
H
8
0
)
e
t
y
B
h
g
i
H
(
E
D
O
C
C
I
T
S
O
N
G
A
I
D
3
H
0
0
)
e
t
y
B
w
o
L
(
E
D
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C
C
I
T
S
O
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G
A
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4
H
0
0
)
e
t
y
B
h
g
i
H
(
A
T
A
D
C
I
T
S
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N
G
A
I
D
5
H
3
0
)
e
t
y
B
w
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L
(
A
T
A
D
C
I
T
S
O
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G
A
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D
6
H
8
E
)
e
t
y
B
h
g
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H
(
M
U
S
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C
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H
C
7
H
3
E
)
e
t
y
B
w
o
L
(
M
U
S
K
C
E
H
C
8
H
D
6
E
T
Y
B
E
L
P
M
A
X
E
S
S
E
R
D
D
A
R
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T
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M
1
H
9
1
N
O
I
T
C
N
U
F
2
H
8
0
)
e
t
y
B
h
g
i
H
(
E
D
O
C
C
I
T
S
O
N
G
A
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D
3
H
0
0
)
e
t
y
B
w
o
L
(
E
D
O
C
C
I
T
S
O
N
G
A
I
D
4
H
0
0
)
e
t
y
B
h
g
i
H
(
A
T
A
D
C
I
T
S
O
N
G
A
I
D
5
H
3
0
)
e
t
y
B
w
o
L
(
A
T
A
D
C
I
T
S
O
N
G
A
I
D
6
H
8
E
)
e
t
y
B
h
g
i
H
(
M
U
S
K
C
E
H
C
7
H
3
E
)
e
t
y
B
w
o
L
(
M
U
S
K
C
E
H
C
8
H
D
6