There can be up to 15 SDM-SIO1As on a single SDM bus. Each SDM-SIO1A will need to be set to a
unique address before they are powered. If any other equipment is present on the bus, whether
an SDM-SIO1A or other SDM device, the user will have to ensure their addresses are unique.
The SDM-SIO4A has a single address switch. This sets the address of the first serial port of the
module (port 1). Other ports have their own SDM address which follow sequentially from the port
1 address. For example, if the address switch is set to 4, port 1 has SDM address 4, port 2 has SDM
address 5, port 3 has SDM address 6, and port 4 has SDM address 7. The equivalent
ComPort
number of each port corresponds to the SDM address of the port in the same way as for the
SDM-SIO1A as shown in
For the SDM-SIO4A, if the address switch is set to “C” (SDM 12) or above, only the ports which
would have valid SDM addresses are enabled. For example, if the switch is set to “E” (14), only
port 1 could be used as sequential addresses above that are not valid.
Table 6-1: SDM address settings
Rotary switch position
SDM address
SerialOpen() instruction
COMPort number
0
0
32
1
1
33
2
2
34
3
3
35
4
4
36
5
5
37
6
6
38
7
7
39
8
8
40
9
9
41
A
10
42
B
11
43
C
12
44
D
13
45
SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
10
