Modbus Plus 5.3
Communications 5-205
Status
Type
MSB
0 16 15
14
13
12
11
10
9
7 64 63
62
61
60
59
58
57
Control Block
The nine control-block registers are assigned in a Peer Cop Health operation as shown:
1st
: 9
2nd
Error Status: This register is filled by the
operation. See MSTR Block Error Codes for a
complete list.
3rd
: Indicates the number of words to transfer.
4th
Word Index: Gives the index of the first Peer Health word
to read.
Routing 1-5: Unused. Set zeros.
Example
Suppose that we have an RMC device on a Modbus Plus network with a node address of 3. We
want to set a coil called ”r;disconnected” when the RMC is not found on the network. We will read
one of the four Peer Cop Global Input Health registers into register 400200. We must first choose
a location for the 9-register control block. In this example, 400130 to 400138 is the location. The
following network would be used:
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