Red Lion PAXCDC5 (PROFIBUS) - Manual (Page 2)

2
INSTALLING AN OPTION CARD
Caution: The option and main circuit cards contain static
sensitive components. Before handling the cards, discharge static
charges from your body by touching a grounded bare metal
object. Ideally, handle the cards at a static controlled clean
workstation. Also, only handle the cards by the edges. Dirt, oil or
other contaminants that may contact the cards can adversely
affect circuit operation.
Warning: Exposed line voltage exists on the circuit boards.
Remove all power to the meter AND load circuits before
accessing the unit.
1. Remove the main assembly from the rear of the case. Squeeze the finger
holds on the rear cover, or use a small screwdriver to depress the side
latches to release it from the case. It is not necessary to separate the rear
cover from the main circuit card.
2. Locate the option card connector for the serial communication card.
Hold the unit by the rear cover, not the display board, when installing an
option card.
3. Install the option card by aligning the option card with the slot in the rear
cover. Be sure the connector is fully engaged and the tab on the option
card rests in the alignment slot on the display board.
4. Slide the assembly back into the case. Be sure the rear cover latches fully
into the case.
Finger
Hold
Finger
Hold
Serial
Communications
Card
Setpoint
Output
Card
Alignment
Slots
Connectors
Main
Circuit
Board
Analog Output
or
Real-Time
Clock Card
TOP VIEW
PRINCIPLE OF OPERATION
The PAX PROFIBUS-DP Card provides the PROFIBUS Network with
access to an Input Data Block (data written to the PROFIBUS Network from the
PAX) and an Output Data Block (data read from the PROFIBUS Network by
the PAX). Using an internal high speed protocol, the card scans each PAX
register in turn, continuously reading Input Data and only writing Output Data
on demand. The PAX registers are mapped into each Input and Output Data
Block, allowing the PROFIBUS Network read/write access to all the registers
in the PAX. The structure of these Data Blocks is described in more detail in
section Data Block Structure.
The Input Data and Output Data Blocks are updated at the end of each scan
of the host PAX Meter. In order to increase the rate that new data is made
available to the PROFIBUS Network, a scheme is employed that reduces the
number of registers polled by the card in each scan to only those that are
required in the application. This Polled Read Mask maps each bit to a PAX
register index which, when set, will force that register to be read from the PAX
Meter. This Polled Read Mask is defined as User Parameter Data and is
described in more detail in section Parameterization.
Due to the cyclic nature of data exchange in the PROFIBUS network
changing Output Data in a slave device, a scheme is employed that indicates
which registers need to be written to the PAX Meter. This Demand Write Mask
maps each bit to a register index which when set, will perform a “once only”
write from the Output Data Block to the PAX Meter. Clearing and re-setting the
bit in the Demand Write Mask will cause the value to be written again. The
Demand Write Mask is part of the Data Block structure and is described in detail
in section Demand Write and Store Request Masks.
STATION ADDRESS
The station address is set using three rotary switches allowing the ID to be set
in standard decimal notation (e.g. address = 123 - SWC = 1, SWB = 2, SWA =
3). Valid addresses range from 0 to 125. If an address greater than 125 is set, the
card will default to a station address of 125.
Note: The card will not default to 125 if set for 999, this number is a special
test mode.
DIAGNOSTIC LEDs
Three LEDs indicate the status of the SPC3 DP Control State Machine (DP),
the Watchdog State Machine (WD) and the PROFIBUS-DP Data Exchange
State (DATA) as shown in Table 1. The LEDs are viewable through the vents on
the top of the PAX case.
Table 1 - LED Indication of PROFIBUS-DP Card Status
LED STATE
CARD STATUS
DP (Red) WD (Green) DATA (Red)
FLASHING FLASHING OFF Bus Not Connected
OFF FLASHING OFF Baud Rate Search
OFF ON OFF Baud Control
FLASHING ON OFF Waiting for Parameterization
ON ON OFF Waiting for Configuration
OFF OFF ON Data Exchange