Delta AH500 Hardware Operation Manual page 470

D0~D65535, and L0~L65535 can be used.

Start address in a slave station: The start address in a slave station is a device address. The default
start address in a slave station is 0. The data in the device addresses in a slave station starting from
the start address in the slave station is read, and the data sent by the master station is stored in the
device addresses in a slave station starting from the start address in the slave station. If the
communication protocol used is the standard Modbus communication protocol, only M0~M8191 and
D0~D32767 can be used. If the communication protocol used is the AH500 communication protocol,
only M0~M8191, D0~D65535, and L0~L65535 can be used. If a slave station is not an AH500 CPU
module, the start address in the slave station must be an absolute address, e.g. 16#1000.

Number of data read from a slave station: The default value is 0. If the devices used are registers, the
unit of data length is a word. If the devices used are contacts, the unit of data length is a bit.

Number of data written into a slave station: The default value is 0. If the devices used are registers,
the unit of data length is a word. If the devices used are contacts, the unit of data length is a bit.

An AH500 series CPU module can modify the data length automatically. If data length is larger than
450/100 (the AH500 communication protocol/the standard Modbus protocol) words, it will be modified
automatically and become 450/100 words. If data length is larger than 7200/1600 (the AH500
communication protocol/the standard Modbus protocol) bits, it will be modified automatically and
become 7200/1600 bits.

A DVP series PLC can modify the data length automatically. If data length is larger than 100 words, it
will be modified automatically and become 100 words. If data length is larger than 1600 bits, it will be
modified automatically and become 1600 bits.

Slave station type: The models which can be connected to the master station can be AH500 series
CPU modules, DVP series PLCs, and other models. (The default value is 0.)

After a CPU module is restored to the factory setting, the slave station address will become the default
value. (The address of the 1
the address of the 32
slave station addresses in SR1756~SR1787 will be read. If a PLC Link is executed, and SM1595 is
OFF, the slave station address in SR1756 will be read. A slave station address must be in the range of
1 to 216. If a slave station address is not in the range, it will become 1.

Device type: The device type used by a slave station must be the same as the device type used by the
master station. For example, if a slave station uses contact devices, the master station must use
contact devices. The legal setting values are 0 (registers) and 1 (contacts). Other values are illegal
values. If the value set is illegal, the slave station will not be involved in a data exchanged. The device
type used for reading in a slave station can be set by means of SR1340, and the device type used for
writing in a slave station can be set by by means of SR1372. (The default values in SR1340 and
SR1372 are 0. (If the reading of data and the writing of data are synchronous, the device type used for
reading must be the same as the device type used for writing.))
Additional remark:
A PLC Link can be executed only if the AH500 series CPU modules runs. If the number of data read from a
slave station and the number of data written into a slave station are 0, no data exchange is performed. If a
PLC Link is executed, the parameters related to the PLC link can not be modified. That is, a slave station
can not be deleted or added if a PLC Link is executed. Only serial ports can be used as communication
interfaces for data exchange performed by means of a PLC Link. (If an AH500 series CPU module used is
AHCPU530-RS2, COM1 must be used for data exchange.)
2. Descriptions of flags:

PLC Link flag: The state of a PLC Link flag indicates whether the corresponding slave station is
connected to the master station. If SM1585 is ON, users can decide whether to connect a slave
station to the master station.

Data exchange flag: The state of a data exchange flag indicates whether the corresponding slave
station and the master station exchange data with each other.

Read error flag: If an error occurs when the master station reads data from a slave station, the
corresponding read error flag will be ON. For example, if the command sent form a slave station is
incorrect, or the checksum in the command sent form a slave station is incorrect, the corresponding
read error flag will be ON.

Write error flag: If an error occurs when the master station writes data into a slave station, the
corresponding write error flag will be ON. For example, if the number of data written into a slave
station is incorrect (is not in a device range), the write error flag will be ON.
st
slave station will be 1, the address of the 2
th
slave station will be 32.) If a PLC Link is executed, and SM1595 is ON, the
C h a p t e r 11 C o n v e n i e n t F u n c t i o n s
nd
slave station will be 2, and
11 - 2 1