LumaSense Technologies IGA 320/23-LO - Manual (Page 14)

IGA 320/23-LO Operating Manual Controls and Connections 14
3.2 Connecting the pyrometer to a PC
The pyrometer is equipped with an RS485 serial interface. With the RS485, long transmission
distances can be realized and the transmission is, to a large extent, free of problems. The RS485
also allows several pyrometers to be connected in a bus system.
If an RS485 connection is not available at the PC, it can be accomplished using the RS485 to USB
connector. When using a RS485 to USB adapter, make sure that the adapter is fast enough to
receive the pyrometer’s answer to an instruction of the master. Most of the commonly used
adapters are too slow for fast measuring equipment, so it is recommended to use the
RS485
USB converter “USB nano“ (ref. no. 3 852 600).
With a slow RS485 connection, it is also possible to set a wait time to the pyrometer (e.g. via the
“Test” field of the software InfraWin, see
Chapter 5 Software Infrawin) which delays the
response of a command to the pyrometer (see also 3.2.2 , Wait time tw).
3.2.1 Connecting to RS485 interface / baudrate
The pyrometer is operating in
half-duplex mode. A1 and A2
as well as B1 and B2 are
bridged in the 8-pin round
connector of the connecting
cable, to prevent reflections
due to long stubs. It also
safeguards against the
interruption of the RS485 bus
system, should a connecting
plug be pulled out. The
master labels mark the
connections on the RS485
converter.
The transmission rate of the
serial interface in Baud (Bd) is
dependent on the length of
the cable. Values between
1200 and 38400 Bd may be set
(via
5 , software InfraWin or the command “br” when using another communication software,
see command table under 7 , data format UPP ® ). The baud rate is reduced by 50% when the
transmission distance is doubled. The typical cable length for 19200 Bd is 2 km.
3.2.2 Wait time tw
When using a pyrometer with RS485, it is possible that the connection is not fast enough to
receive the pyrometer’s answer to an instruction of the master. In this case, a wait time
(between 00 and 99 bit) can be set to slow down the data transfer (e.g.: tw = 02 at a baud rate
9600 means a wait time of
2 /
9600
sec).
2
3
4
5
1
7
6
8
2
3
4
5
1
7
6
8
2
3
4
5
1
7
6
8
A
B
B
1
A
2
B
2
A
1
B
1
A
2
B
2
A
1
A
2
B
2
A
1
B
1
Master
Pyrometer 1
e.g. address 00
Pyrometer 2
e.g. address 01
Pyrometer 32
e.g. address 31
Terminator
120 Ohm
S
G
R
N
D
G
R
N
D
G
R
N
D