Rosemount 890, Instruction Manual

Page: 75 / 96

R
OUTINE
S
ERVICE
748460-A
6-11
Rosemount Analytical
January 2000
M
ICRO
B
OARD
R
EPLACEMENT
All original calibration constants and settings stored in non-volatile memory must be re-
entered when the Micro Board is replaced. These procedure are given in Section 3.
6.4.6 C
ASE
H
EATER
T
EMPERATURE
C
ONTROL
The Case Heater Control is included on the Power Supply Board. The setpoint is
47
°
C.
The sensor is a resistor with a positive temperature coefficient (1.925 ohms/
°
C). The
resistance is 500 ohms at 0
°
C.
6.4.7 D
UAL
A
LARM
/C
ALIBRATION
G
AS
C
ONTROL
B
OARD
(O
PTION
)
This board is used for both dual alarm and calibration gas control, depending on the
position of the jumper in the jumper-selectable address. This is a peripheral circuit
function which communicates with the computer via an 8-bit bus arrangement. This
option consists of two form C contacts, rated 3A 125-250 VAC or 5A 30 VDC
(resistive). This circuit board satisfies a dual alarm requirement, as it provides two
medium power relays that can be independently controlled from the central processor.
Also, the board can be used to connect user-supplied solenoid valves to zero and
span calibration gases for one-man calibration. Provision is made for assigning a
specific address in the range 0 through 7 using jumpers. See Table 6-1.
6.4.8 I
SOLATED
R
EMOTE
R
ANGE
I/O B
OARD
(O
PTION
)
The Remote Range I/O Board is a peripheral circuit function which communicates with
the computer via an 8-bit bus arrangement. This provides isolated two-way
communication between the host instrument and external user devices. Provision is
made to assign a specific address in the range 0 through 7 using jumpers. See Table
6-1.
6.4.9 A
UTO
Z
ERO
/S
PAN
B
OARD
(O
PTION
)
The Auto Zero/Span Board is a peripheral circuit function which communicates with
the computer via an 8-bit bus. With the appropriate software, it satisfies the auto
zero/span requirement. It provides six form C relay contact outputs, four of which are
suitable for medium power requirements, the remaining two are relegated to alarm of
indicator functions. Snubbers are provided for the medium power relays. Provision is
made to assign a specific address in the range 0 through 7 using jumpers. The auto-
cal request bit is level triggered and therefore, the request line must be brought low
before the analyzer completes the auto-cal process. See Table 6-1.