INFICON BPG400 ATM to Ultra-High Vacuum Gauge User Manual
Page 38
38
tina03e1-b (2004-02) BPG400 v1.om
For unambiguous identification of the gauge in a RS485 bus environment, a device
address is required.
The device address (base address) setting is primarily made on the gauge. Via
RS485 communication, an address offset can be added from the host:
Operating device address
=
base address
+ offset
where:
Operating device address
00 … 7F
hex
1)
aa
(
→ 39)
Base address
00 … 7F
hex
Gauge setting (switches,
→ below)
Offset
00 … 7F
hex
From host, oo (
→ 39)
1)
Sum of base address and offset must not exceed 7F
hex
The base address (0 … 127
dec
) is set in hexadecimal form
(00 … 7F
hex
) via the "ADDRESS", "MSD", and "LSD" switches.
The address is polled by the firmware when the gauge is
switched on only. If the address set by the switches is above the
allowed range, all parameters are set to the factory default val-
ues. Communication is not possible in this case.
Commands sent by the host must include the following elements:
Element:
Start character
Operating
device address (aa)
_
3)
Data
1)
Terminator
Value:
#
00 … FF
hex
Space
→ "commands
and responses"
CR
2)
1)
Characters can be upper or lower case.
2)
Carriage return (0D
hex
or ctrl M)
3)
A Space character is signified by a "_" (underline) character in the text.
The response message returned by the BPG400-SR has the following structure:
Element:
Start character
Operating
device address (aa)
_
3)
Data
1)
Terminator
Value:
*
00 … FF
hex
Space
→ "commands
and responses"
CR
2)
1)
Characters returned by the BPG400-SR are always upper case.
2)
Carriage return (0D
hex
or ctrl M)
3)
A Space character is signified by a "_" (underline) character in the text.
If an incorrect data string is sent by the host, the BPG400-SR will return an error
message with the following structure:
Element:
Start character
Operating
device address (aa)
_
3)
Data
1) 3)
Terminator
Value:
?
00 … FF
hex
Space
ERROR
CR
2)
1)
Characters returned by the BPG400-SR are always upper case.
2)
Carriage return (0D
hex
or Ctrl M)
3)
A Space character is signified by a "_" (underline) character in the text.
4.9.2.2 Device Address
4.9.2.3 Command Structure
(Host)
4.9.2.4 Response Structure
4.9.2.5 Error Messages