ProSoft Technology PTQ-AFC - Manual (Page 243)

PTQ-AFC ♦ Modicon Quantum Platform Reference
Liquid and Gas Flow Computer for Hydrocarbon Products User Manual
ProSoft Technology, Inc. Page 243 of 259
June 23, 2011
11.9.3 Why can't the AFC Manager connect to the module?
Check the cable used in your project: a null-modem cable should be used to
connect the module with the local PC serial port. Make sure that the baud rate,
data bits, mode, parity and primary slave address are the same (both in PC and
module).
If you change the primary slave address and later forget the new address, the
module will not establish communications. You must read the primary slave
address value (address 100) over the backplane using the Modbus Gateway
Transaction Block.
11.9.4 Why do I have to enable or disable a meter?
A meter channel will only perform flow calculation if it is enabled. For
performance reasons you should disable all meter channels that are not being
used. You cannot change a meter type and/or product group for a meter channel
that is currently enabled.
11.9.5 Why does the card not calculate results, or why did it stop
calculating results?
This could be caused by a couple of things.
1
The first thing to check is that the module actually received a clock. If the card
does not get a clock it will not be able to schedule storage of historical
records.
2 The next possibility is that the meter is not enabled or some parameter for the
run is not correct. Check to see if the run is enabled and that no errors exist
in configuration or data for the run in question. Check for alarms arising from
the calculations. The AFC Manager software can be a great help with this as
it will highlight problem areas.
11.9.6 What is the Virtual Modbus Slave?
The AFC Modbus database can be accessed using the Primary Modbus Slave
address. More than 100.000 registers may be accessed using this slave.
You may want to use certain values from the Modbus database in a different
order than the one presented in the Primary Modbus Slave. One example is if
you want to poll certain values from the Modbus database using a Modbus
master device in the field. Instead of using several commands to poll from
different locations in the Modbus database, it is better to remap these values to
other locations in order to optimize the master polling.
This is the reason the AFC module offers a second slave: the Virtual Modbus
Slave. Using the AFC Manager software, you can remap up to 20.000 registers
from the Primary Modbus Slave in any order. The Virtual Modbus Slave Address
must be configured using the AFC Manager software (Site Config dialog box).
The Virtual Modbus Slave is also used when using the Modbus Pass-Thru
function block.