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Modicon Communication Driver Manual
The following is the format for a global data bit read from a Operator Station:
[GLBL,G00rr bb] or [GLBL, G00rr.bb]
rr Operator Station reference number of the register.
bb Operator Station reference number of the bit position. The bit positions are numbered from 1 to
16, least significant to most significant.
Note:
An Operator Station cannot directly read or write to another Operator Station.
Note:
An Operator Station’s most significant bit (MSB) is bit 16 and the Modicon PLC’s most
significant bit (MSB) is 1. Refer to the figure below.
Unsolicited Writes to the Operator Station with Modbus Plus
An Operator Station can receive unsolicited writes from a Modicon controller provided the Operator
Station and the specified address is referenced in the Operator Station. The Modicon controller
performs unsolicited writes through the use of the MSTR function block.
The Master Function Block consists of 4 main components: the control block, data start, data size, and
the enable input.
The Control Block -
This block must be configured as follows:
4TTTT
Operation Type (1 for write)
4TTTT+1 Error
Status
(reported by controller)
4TTTT+2 Length
4TTTT+3
Slave Device Data Area
4TTTT+4 Routing
1
4TTTT+5
Routing 2
Complete path to the Operator
4TTTT+6 Routing
3 Station from controller
4TTTT+7 Routing
4
4TTTT+8 Routing
5
Note:
The routing address after the Operator Station address should be set to one. Any unused
routing addresses should be set to zero.
