Instruction Manual

Logic Functions - Book 1
MODCELL SERIAL COMMUNICATION BLOCK
4-20
4.3.1 Modcell Serial Communication Block Modbus Slave Capabilities
The MSC block is responsible for reading and writing instrument attributes. The MSC block
executes once every 50 milliseconds. The Modbus memory types supported are:
Memory Location Memory Type
0XXXX Read/Write Discrete Points
1XXXX Read Only Discrete Points
30XXX Read Only Single Registers
31XXX Read Only Multiple Registers
40XXX Read/Write Single Registers
41XXX Read/Write Multiple Registers
A subset of the Modbus function codes are supported by MODCELL. The function codes
supported by MODCELL are listed in the following table along with the maximum number of
values the function can read or write. For more information on all Modbus function codes,
refer to the January 1985 version of the Gould Modbus Protocol Reference Guide.
Function Maximum Values
Code Description to Read/Write
01 Read discrete points from (00001 - 00099) 99 points
01 Read discrete points from (00101 - 00199) 99 points
01 Read discrete points from (00201 - 00299) 99 points
01 Read discrete points from (00301 - 00399) 99 points
01 Read discrete points from (00401 - 00499) 99 points
02 Read discrete points from (10001 - 10099) 99 points
02 Read discrete points from (10101 - 10199) 99 points
02 Read discrete points from (10201 - 10299) 99 points
02 Read discrete points from (10301 - 10399) 99 points
02 Read discrete points from (10401 - 10499) 99 points
03 Read registers from (40001 - 40099) 32 registers
03 Read registers from (40101 - 40199) 32 registers
03 Read registers from (40201 - 40299) 32 registers
03 Read registers from (40301 - 40399) 32 registers
03 Read registers from (40401 - 40499) 32 registers
03 Read registers from (41001 - 41999) 125 registers
03 Read registers from (42001 - 42999) 125 registers
03 Read registers from (43001 - 43999) 125 registers
03 Read registers from (44001 - 44999) 125 registers
03 Read registers from (45001 - 45999) 125 registers
04 Read registers from (30001 - 30099) 32 registers
04 Read registers from (30101 - 30199) 32 registers
04 Read registers from (30201 - 30299) 32 registers
04 Read registers from (30301 - 30399) 32 registers
04 Read registers from (30401 - 30499) 32 registers
04 Read registers from (31001 - 31999) 125 registers
04 Read registers from (32001 - 32999) 125 registers
04 Read registers from (33001 - 33999) 125 registers
04 Read registers from (34001 - 34999) 125 registers
04 Read registers from (35001 - 35999) 125 registers