User`s guide

Page 73

Controlinc 1746-C (Version 5.21) Network Master Users Guide (2004-11-18)

5.4.13. Table [15]: Additional Block of Registers Being Polled From 1

Actuator

Words [4  63] PLC access: Read / Write

TABLE FORMAT:

This operation allows the operator the chance to poll a single actuator for a block of registers.

The register values returned are stored in table [15] such that …

• Words [4 - 7] … header information about information returned …

 Word [4] … Valve address where block of data came from.

 Word [5] … Valve (actuator) type id.

 Word [6] … Starting holding register number.

 Word [7] … Total Number of registers in block.

• Words [8 - 13] … not used … reserved.

• Words [14 - 63] … register information returned.

TABLE CONTROL:

Control of this operation is via 4 words in table [0] such that …

• Table [0] – Word [11] … The actuator address to get the block of registers from.

• Table [0] – Word [12] … The register number for the 1

holding register in the block to retrieve.

• Table [0] – Word [13] … The total number of registers to retrieve.

• Table [0] – Word [14] … This is a flag that indicates whether or not to start requesting that block

of registers from that actuator when polling it.

If Table [0] – Word [14] == 0 do not poll for the block of registers.

If Table [0] – Word [14] =/= 0 (any non-zero value) … poll for the block of registers.

By default, Table [0] – Words [11

 14] == 0 … do not poll.

OPERATIONAL OVERVIEW:

This data is retrieved with a separate Modbus read command when the particular actuator is being

polled (scanned).

The PLC may reset this table with any value is prefers. To do this, the PLC must insert the new value

into the table and send it to the 1746-C as a write command. The values in this table are not sent out

to the actuators on the network.

A read back of Table [15] will

• If a write command issued: reflect the write command accepted by the 1746-C except words [4

– 13] are zeroed out.

• If a read command issued: reflect the last known values in the table.