7. OPERATION
ADA-4040PC8 is a bidirectional converter of JCT-ASCII protocol to MODBUS-RTU protocol, with the possibility of converting the baud
rate, data format (number of data bits, parity bit, stop bits) and the type of RS485 interface to RS422.
Additionally, it is a separator of the JCT-ASCII port from the MODBUS-RTU port.
ADA-4040PC8 reads data from the JCT-ASCII controller and properly processed, saves it to the MODBUS-RTU protocol registers
described in the section IMPLEMENTATION OF THE MODBUS-RTU PROTOCOL.
MODBUS protocol frames with the CRC error are rejected by the converter.
JCT-ASCII protocol frames with a checksum error are rejected by the converter.
In case of no response from the JCT-ASCII controller, the ADA-4040PC8 converter corresponds to the MODBUS protocol exception
described in the section EXCEPTIONS OF THE MODBUS-RTU PROTOCOL.
Fig. 9. Connecting VIRAP* JCT control systems to the MODBUS-RTU RS485 bus
11
ADA-4040PC8
SCADA
MASTER
MODBUS-RTU
SLAVE
MODBUS-RTU
DEVICE
ADA-1040
ADA-4040PC8
SLAVE
MODBUS-RTU
DEVICE
ADA-4040PC8
RS-232
T
ra
n
s
m
is
s
io
n
9
60
0
b
p
s
/
8
/
N
/
1
T
ra
n
s
m
is
s
io
n
9
60
0
b
p
s
/
8
/
N
/
1
JCT-1
Controller
JCT-1
Controller
