Manual
Analog Panel Meter  Instruction Manual 
74
Modbus RTU Serial Communications (serial) 
The meter is equipped with serial communications capability as a 
standard feature using Modbus RTU Serial Communication Protocol. 
To communicate with a computer or other data terminal equipment, an 
RS-232 or RS-485 option is required; see Ordering Information on 
page 7 for details. 
Warning! 
Do not connect any equipment other than Dwyer 
Instruments, Inc.’s expansion modules, cables, or 
meters to the RJ45 M-LINK connector. Otherwise 
damage will occur to the equipment and the meter. 
Note: More detailed instructions are provided with each optional serial 
communications adapter. 
Note: Refer to the Modbus
Register Tables located at www.dwyer-
inst.com for details. 
When using more than one meter in a multi-drop mode, each meter must 
be provided with its own unique address. The meter address (Slave ID) 
may be programmed between 1 and 247. The transmit delay may be set 
between 0 and 199 ms. The parity can be set to even, odd, or none with 
1 or 2 stop bits. 
The APM can also be connected to another APM with a special PMA-02 
cable, allowing the user to copy all the settings from one meter to 
another, using the Copy function. 










