ProSoft Technology MVI69-DFCM User Manual page 16

Functional Overview
State
0
1
2
3
Slaves are defined to the system when the module initializes the master command list.
Each slave defined will be set to a state of one in this initial step. If the master port fails
to communicate with a slave device (retry count expired on a command), the master will
set the state of the slave to a value of 2 in the status table. This suspends
communication with the slave device for a user specified scan count (Error Delay Count
parameter in the configuration file). Each time a command in the list is scanned that has
the address of a suspended slave, the delay counter value will be decremented. When
the value reaches zero, the slave state will be set to one.
In order to read the slave status table, you should refer to the sample ladder logic. The
ladder logic must send a special block to the module to request the data. Each port has
a specific set of blocks to request the data as follows:
BLOCK ID
3002
3003
3004
3005
3006
3102
3103
3104
3105
3106
The format of these blocks is as shown below:
Write Block – Request Slave Status
Offset
0
1 to n
n=60, 120, or 240 depending on what is entered in the Block Transfer Size parameter
(see the configuration file).
10
Description
The slave is inactive and not defined in the command list
for the master port.
The slave is actively being polled or controlled by the
master port and communications is successful.
The master port has failed to communicate with the slave
device. Communications with the slave is suspended for
a user defined period based on the scanning of the
command list.
Communications with the slave has been disabled by the
ladder logic. No communication will occur with the slave
until this state is cleared by the ladder logic.
DESCRIPTION
Request status for slaves 0 to 59 for Port 1
Request status for slaves 60 to 119 for Port 1
Request status for slaves 120 to 179 for Port 1
Request status for slaves 180 to 239 for Port 1
Request status for slaves 240 to 255 for Port 1
Request status for slaves 0 to 59 for Port 2
Request status for slaves 60 to 119 for Port 2
Request status for slaves 120 to 179 for Port 2
Request status for slaves 180 to 239 for Port 2
Request status for slaves 240 to 255 for Port 2
Description
3002 – 3006 or 3102 – 3106
Spare
Length
1
n
ProSoft Technology, Inc.
MVI69-DFCM User Manual
June 24, 2004