28: AS-INTERFACE MASTER COMMUNICATION
28-2 « FC4A MICROSMART USER’S MANUAL »
AS-Interface System Requirements
Master
The AS-Interface master controls and monitors the status of slave devices connected to the AS-Interface bus.
Normally, the AS-Interface master is connected to a PLC (sometimes called ‘host’) or a gateway. For example, the Micro-
Smart
AS-Interface master module is connected to the MicroSmart CPU module.
The FC4A MicroSmart CPU module can be used with one AS-Interface master module to set up one AS-Interface net-
work.
The AS-Interface master module can connect a maximum of 62 digital I/O slaves. A maximum of seven analog I/O slaves
can also be connected to the AS-Interface master module (compliant with AS-Interface ver. 2.1 and analog slave profile
7.3).
Slaves
Various types of slave devices can be connected to the AS-Interface bus, including sensors, actuators, and remote I/O
devices. Analog slaves can also be connected to process analog data.
Slaves are available in standard slaves and A/B slaves. Standard slaves have an address of 1 trough 31 in the standard
address range. A/B slaves have an address of 1A through 31A in the standard address range or 1B through 31B in the
expanded address range. Among the A/B slaves, slaves with an address of 1A through 31A are called A slaves, and slaves
with an address of 1B through 31B are called B slaves.
• The AS-Interface master module cannot be connected to the all-in-one 10-I/O and 16-I/O type CPU
modules.
• One AS-Interface master module can be connected to the FC4A
MicroSmart CPU module. If more
than one AS-Interface master module is connected, an error occurs and special data register D8037
(quantity of expansion I/O modules) stores error code 40 (hex).
• Normally, a maximum of four expansion I/O modules can be connected to the all-in-one 24-I/O
type CPU module. But when an AS-Interface master module is connected, only a total of three
expansion modules can be connected, including the AS-Interface master module. Do not connect
more than three expansion modules due to the amount of heat generated. If more than three expan-
sion modules, including the AS-Interface master module, are connected, an error occurs and special
data register D8037 (quantity of expansion I/O modules) stores error code 20 (hex).
• Similarly, slim type CPU modules can normally connect a maximum of seven expansion I/O mod-
ules, but can connect a maximum of six expansion modules including one AS-Interface master mod-
ule. If more than six expansion modules, including the AS-Interface master module, are connected,
an error occurs and special data register D8037 (quantity of expansion I/O modules) stores error
code 20 (hex).
• The AS-Interface master module can connect a maximum of seven analog I/O slaves. When more
than seven analog I/O slaves are connected, the AS-Interface system will not operate correctly.
can be mounted.
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